McANDREW'S  FLOATING 
SCHOOL 

A  STORY  FOR  MARINE  ENGINEERS 


BY 


CAPTAIN  C.  A.  MCALLISTER 

Engineer-in-Chief  United  States  Eevenue  Cutter  Service, 
Washington,  D.  C. 

Author  of  "The  Professor  on  Shipboard" 

and  many  other  Engineering 

stories- 


38  ILLUSTRATIONS 


NEW   YORK   AND   LONDON 

INTEKNATIONAL  MAKINE  ENGINEERING 
1914 


REPRINTED  FROM 
INTERNATIONAL  MARINE  ENGINEERING 

COPYRIGHT  1914 
BY  ALDRICH  PUBLISHING  CO. 


Introduction 

In  presenting  these  lectures  of  "McAndrew"  in 
book  form,  the  author  does  so  in  the  hope  that  they 
may  be  of  benefit  to  some  of  that  great  class  of  hard 
workers  whose  life  "below  the  grating"  is  but  little 
understood  by  the  public  at  large.  These  men  are  the 
backbone  of  modern  seafarers,  as  they  bear  the  heat 
and  burden  of  the  work  of  sea  transportation.  Inured 
from  early  youth  to  the  hardest  physical  toil  known  to 
man,  it  is  scarcely  to  be  presumed  that  their  early  edu- 
cation is  such  as  to  fit  them  for  the  higher  positions  in 
engineering;  for  example,  those  held  by  the  licensed 
engineer  officers  under  whom  they  serve. 

Yet  all  who  come  in  contact  with  them  know  that 
there  is  not  another  class  of  workers  in  any  branch  of 
industry  containing  so  large  a  number  of  young  men 
ambitious  to  reach  higher  positions.  Such  ambition, 
of  course,  requires  considerable  study  of  the  elements 
of  engineering.  It  must  be  admitted  that  even  the  sim- 
plest of  text-books  on  engineering  subjects  are  couched 
in  such  language,  or  so  hampered  by  mathematical 
formulae,  plain  as  they  may  be  to  those  whose  rudi- 
mentary education  permits  them  to  grasp  their  mean- 
ing, as  to  defeat  their  very  purpose. 


It  has  therefore  been  the  aim  in  this  course  of  lec- 
tures to  present  abstruse  engineering  facts  in  a  simple 
and,  it  is  hoped,  as  interesting  a  manner  as  possible. 
Should  it  succeed  in  helping  some  of  that  type  for 
whom  it  has  been  written,  the  writer  will  feel  much 
encouraged.  Certainly  these  men,  the  oilers,  coal- 
passers,  watertenders  and  firemen. of  the  world's  mer- 
chant marine  are  deserving  of  the  efforts  of  all  who 
can  be  of  any  assistance  to  them.  The  transformation 
from  sail  to  steam  on  the  great  oceans  of  the  world  has 
been  so  rapid  that  poets  and  writers  generally  are  still 
sounding  the  praises  in  song  and  story  of  the  old-time 
manner  and  have  not  awakened  to  the  fact  that  the 
sailor  has  been  replaced  by  the  man  in  the  fireroom  or 
engine-room.  Some  of  the  romance  of  the  sea  has  dis- 
appeared with  the  sailorman,  but  heroism  is  as  much, 
and  more,  in  evidence  with  his  begrimed  successor. 
Where  in  the  annals  of  seafarers  was  ever  shown 
greater  heroism  than  that  displayed  by  the  engineer's 
force  of  the  ill-fated  Titanic,  who,  almost  to  the  man, 
sank  with  their  ship  and  at  their  posts  of  duty?  All 
the  world  knows  that  these  hundreds  of  brawny  ar- 
tisans of  the  deep  could  have  seized  the  boats  and  es- 
caped with  their  lives ;  but  they  were  men,  and  it  is  for 
the  thousands  of  men  like  them  that  this  book  i? 
written. 

G.  A.  MCALLISTER. 


CONTENTS. 


PAGE 
CHAPTER  T. 

Introducing  James  Donald  McAndrew .  9 

CHAPTER  II. 

School    Opens -.  ...        14 

CHAPTER  III. 

Force,  Work  and  Power, 


CHAPTER  IV. 

Heat,  Combustion 

and  the  Generation  of  Steam.  .  .  . 

21 

CHAPTER  V. 

Engineering    Materials  

30 

CHAPTER  VI. 

Boilers  

39 

CHAPTER   VII. 

Boiler  Fittings.  .  . 

49 

CHAPTER  VIII. 

Forced  Draft  .... 

57 

CHAPTER  IX. 

Engines   

62 

CHAPTER  X. 

Valves  and  Valve 

Gear  

77 

CHAPTER   XI. 

Engine  Fittings.  . 

87 

CHAPTER  XII. 

Condensers,  Air  and  Circulating  Pumps  ..........      100 

CHAPTER  XIII. 

Feed  Water  Filters,  Pumps  and  Injectors  .........      112 

CHAPTER  XIV. 

Evaporators  and  Distillers.  ...  .................      123 

CHAPTER  XV. 

Electricity  ..............................  ^7 

CHAPTER  XVI. 

Pipes  and  Valves  ............................. 


CHAPTER  XVII. 

Indicators  and  Horse  Power  ...................        149 

CHAPTER  XVIII. 

Care  and  Management  of  Boilers  ................      162 

CHAPTER  XIX. 

Care  and  Management  of  Engines  and  Auxiliaries.  .      178 

CHAPTER  XX. 

Examination  Questions  and  Answers  .........  195 


McAndrew's  Floating   School 

CHAPTER  I 

Introducing  James  Donald  McAndrew 

"I'm  tired  of  shoveling  coal  and  being  bossed  around,"  re- 
marked Tom  O'Rourke,  one  of  a  party  of  four  husky  young 
fellows  who,  at  the  end  of  a  voyage,  were  just  banking  the 
fires  in  the  stokehold  on  board  the  coasting  steamer  Tusca- 
rora,  then  lying  at  her  pier  on  the  East  River.  This  remark 
brought  about  a  general  laugh  from  the  other  members  of 
the  party.  "Well,"  replied  Jim  Pierce,  after  the  laugh  had 
subsided,  "what  are  you  going  to  do  about  it?  That's  just 
what  I've  been  thinking  prttty  strongly  about ;  here  I've  been 
three  years  on  this  packet,  working  like  a  dog,  and  I  don't 
see  any  chance  of  my  ever  getting  anything  better  to  do ;  of 
course,  after  a  while,  I  may  get  a  chance  to  squirt  oil  on  that 
old  mill  of  ours,  but  what  I  want  to  do  is  to  get  a  'ticket'  and 
boss  the  job  myself." 

"Well,  why  don't  you,"  rejoined  Henry  Nelson,  another 
member  of  the  party.  "The  Chief  told  me  the  other  day  that 
he  had  worked  himself  up  from  the  bunkers,  and  he's  pretty 
good  at  figures,  too.  If  we  only  had  the  head  on  us  that  he 
has,  we  needn't  wait  long  before  the  steamboat  inspectors 
would  pass  us  out  the  right  kind  of  a  paper." 

Gus  Schmidt,  the  fourth  member  of  the  party,  had,  during 
all  this  conversation,  stood  by  quietly,  drawing  great  puffs 
of  smoke  out  of  his  five-cent  meerschaum,  and  taking  in 
everything  that  was  said.  As  became  his  German  ancestry, 


10  MC  ANDREW'S  FLOATING  SCHOOL 

he  was  stolid  of  disposition  and  not  given  to  saying  much  un- 
less he  had  something  to  say.  Finally,  after  he  thought  it  was 
his  turn  to  get  into  the  conversation,  he  said:  "You  fellows 
make  me  tired  with  all  your- pipe- dreams ;  why  don't  you  get 
down  to  business;  now  I'll  tell  you  what  let's  do.  I  just 
heard  the  'Super'  on  the  dock  say,  to-day  that  the  bunch  of 
kettles  in  this  ship  are  to  come  out,  that  we  are  going  around 
to  Philadelphia  to  get  some  new  ones,  and  the  ship  is  to  be 
given  a  general  overhauling  at  the  same  time/ so- as  to  put 
her  in  good  shape  for  the  next  season's  work.  The  Chief  is 
going  to  boss  the  repairs,  and  the  four  of  us  are  going  to  be 
kept  by  to  chip  and  paint  the  coal  bunkers  and  do  some  other 
high-class  stunts  like  that.  The  whole  job  will  last  about  six 
months,  and  as  we  won't  have  anything  particular  to  do  at 
night,  let's  buy  some  books  and  get  the  'old  man'  to  play 
school  teacher  for  us." 

"Fine  business,  Dutchy,"  said  O'Rourke ;  "you've  got  a  head 
on  you  like  a  clock.  We'll  go  to  it."  The  idea  also  met  the 
approval  of  the  other  two,  and  it  was  decided  to  brace  the 
genial  Chief  with  the  proposition. 

James  Donald  McAndrew  was  a  young  man,  not  of  French 
descent,  as  you  no  doubt  may  have  surmised  by  this  time,  who 
was  born  on  the  great  East  Side  in  New  York  some  thirty- 
eight  years  ago.  Educated  in  the  public  schools  until  he  was 
fourteen,  he  had  successfully  served  an  apprenticeship  in  a 
big  general  repair  shop  on  the  waterfront,  and  at  the  same 
time  had  gone  to  night  school  at  Cooper  Union,  where,  being 
naturally  bright,  he  had  become  thoroughly  grounded  in  the 
rudiments  of  an  engineering  education.  Being  fond  of  the 
water,  he  had  shipped  on  board  a  twenty-five  hundred  ton 
steamer  as  a  fireman,  and  in  a  very  short  time  had  taken  out 
his  license  as  a  Third  Assistant.  Being  naturally  a  hustler 
and  capable  of  making  friends  among  his  superior  officers, 
he  found  himself  at  the  age  of  thirty-eight  the  Chief  Engi- 


JAMES  DONALD   MC  ANDREW  H 

neer  on  the  Tuscarora,  the  biggest  ship  of  the  line.  It  was 
therefore  quite  in  keeping  that  the  Superintendent  should 
have  selected  him  as  inspector  of  the  extensive  repairs  the 
ship  was  about  to  undergo.  Unlike  many  young  men  of  his 
age  who  lead  a  seafaring  existence,  he  took  life  somewhat 
seriously  and  had  gone  through  the  trying  years  of  his  devel-^ 
opment  without  falling  into  any  bad  habits.  His  father  had 
died  when  the  young  man  had  just  started  in  as  a  Third 
Assistant,  which  left  upon  him  the  responsibility  of  looking 
after  his  widowed  mother  and  two  young  sisters.  Conse- 
quently he  was  not  given  to  wasting  his  money  and  could  be 
found  generally  attending  strictly  to  his  business  instead  of 
roaming  around  town  at  nights  when  the  ship  was  in  port. 
His  kindly  disposition,  ready  wit  and  general  all-around  abil- 
ity had  won  for  him  the  respect  of  the  crew,  so  he  was  not 
at  all  surprised  this  particular  evening  upon  opening  his  state- 
-room door  in  response  to  a  knock  to  find  four  members  of 
the  fireroom  gang,  hats  in  their  hands,  Banding  on  the  out- 
side. "Well,  boys,  what  can  I  do  for  you?"  was  his  cheerful 
salutation. 

O'Rourke,  the  self-constituted  spokesman  of  the  party, 
blurted  out:  "You  see,  Chief,  it's  this  way;  us  four  young- 
sters have  an  idea  that  we  would  like  to  get  ahead  in  the 
world,  and  there  don't  seem  to  be  much  of  a  show  for  us  if 
we  don't  get  something  in  our  heads.  Dutchy  Schmidt  here 
thinks  that  if  we  will  get  some  books,  you  might  help  us  out 
when  we  get  around  to  Philadelphia  this  winter  putting  in 
the  new  boilers.  We'll  have  every  night  in,  and  as  we  will  all 
live  on  the  ship,  we  thought  as  how  you  might  teach  us 
something  for  an  hour  or  so  every  night.  We'll  make  it  all 
right  with  you  for  the  time  you  give  us.  What  we  want  rs 
to  be  able  to  get  out  our  'tickets'  from  the  steamboat  inspec- 
tors, and  we  know  that  you  can  give  us  the  right  steer." 

"So  you  want  to  make  me  a  school  teacher,  eh?"  laughingly 


12  MC  ANDREW'S  FLOATING  SCHOOL 

rejoined  Me  Andrew.  "That  isn't  a  bad  idea,  though,  and  if 
you  fellows  mean  business  and  will  get  right  down  to  brass 
tacks  I  might  consider  it.  I  want  to  tell  you  one  thing  right 
now,  and  that  is  if  I  do  undertake  such  a  job  I  don't  want  any 
monkey  business.  You'll  have  to  study  hard  or  you'll  find 
me  worse  than  any  old  Yankee  schoolmaster  you  ever  dreamed 
of.  Before  I  sign  up  on  this  proposition  I  want  to  know 
something  about  each  of  you.  Of  course  I  know  you  are  all 
pretty  good  firemen  and  'tend  to  business,  but  what  I  must 
find  out  from  each  of  you  is  something  about  how  much  of  an 
education  you  have.  I  know  you  are  not  graduates  of  a  high 
school  or  you  wouldn't  be  here  flirting  with  a  slice-bar  and 
wrestling  with  clinkers  for  a  living.  O'Rourke,  let's  hear  your 
spiel  first." 

"Well,  sir,"  replied  that  worthy,  "I  ain't  much  on  book 
learning,  but  I  can  write  pretty  well,  understand  arithmetic, 
have  studied  geography  and  know  a  little  something  about  his- 
tory. When  I  was  a  boy  I  used  to  know  the  Catechism  from 
one  end  to  the  other,  but  I'm  a  little  shy  on  that  now." 

"Never  mind,"  said  McAndrew,  "this  will  be  no  Sunday 
school  you  are  going  to  tackle.  How  about  you,  Nelson  ?" 

That  descendant  of  some  Norse  king  gave  an  outline  of 
his  educational  career  which  closely  corresponded  with 
O'Rourke's,  excepting  the  Sunday  school  part.  Schmidt  and 
Pierce  followed  in  about  the  same  strain,  so  that  the  upshot 
of  it  all  was  that  Mr.  McAndrew  considered  his  contemplated 
class  was  about  on  a  par  so  far  as  their  proposition  was  con- 
cerned. 

"I  can  see  right  now  that  I  am  up  against  a  hard  proposition 
to  train  you  fellows  up  so  as  to  enable  you  to  take  out  your 
papers,  but  as  long  as  you  mean  business  I  am  willing  to  try 
out  your  scheme,"  said  the  Chief. 

"Thank  you,  sir,"  was  the  chorused  reply  from  all  four,  as 
light-heartedly  they  took  their  departure.  Had  they  been  col- 


JAMES  DONALD    MC  ANDREW  13 

lege  boys  one  of  them  would  probably  have  yelled  out, 
"What's  the  matter  with  McAndrew?"  to  be  self-answered  in 
a  raucous  yell,  "He's  aH  right,"  etc.,  but  they  had  not  yet 
reached  that  high  degree:  if  culture. 


CHAPTER  II 

School  Opens 

About  two  weeks  later  the  Tuscarora  steamed  up  the  Dela- 
ware River  to  the  shipyard  where  the  repairs  were  to  be  made, 
fires  were  hauled,  most  of  the  crew  discharged  and  prepara- 
tions made  to  begin  the  work.  The  four  young  firemen  and 
Mr.  McAndrew  were  kept  very  busy  for  a  time  after  the 
arrival  of  the  ship,  but  it  was  finally  decided  that  the  school 
should  begin  on  what  happened  to  be  the  first  Monday  night  of 
the  month.  The  youngsters  in  the  meantime  had  rigged  up 
a  pretty  fair  school  room  in  the  engineer's  storeroom,  and 
had  hung  up  a  good-sized  blackboard  on  one  of  the  bulkheads. 
No  testimony  was  given  as  to  just  where  they  obtained  this 
blackboard,  but  it  is  safe  to  say  that  the  shipyard  people  must 
have  contributed  involuntarily  from  their  pattern  and  paint 
shops  toward  the  cause  of  education. 

Monday  night,  shortly  after  supper,  the  first  session  of  the 
McAndrew  School  commenced  without  any  frills  or  formali- 
ties. There  was  no  necessity  for  a  roll-call,  as  a  full  attend- 
ance was  in  evidence.  O'Rourke,  Pierce,  Nelson  and  Schmidt 
had  each  indulged  in  a  clean  shave  for  the  momentous  occa- 
sion, and  McAndrew  himself  appeared  a  little  more  perked 
up  than  usual  in  honor  of  his  debut  as  a  teacher. 

Assuming  a  demeanor  somewhat  in  keeping  with  his  new 
responsibilities,  McAndrew  addressed  his  class  as  follows: 
"Young  men,  we  are  about  to  start  in  oui  course  of  training. 


SCHOOL  OPENS  15 

I  don't  propose  to  turn  out  a  lot  of  high-brows  from  this 
floating  school,  but  what  I  do  intend,  if  possible,  is  to  drive 
enough  theory,  or  whatever  you  call  it,  into  you  to  enable  you 
with  practical  experience  to  pass  your  examinations  for  a 
license  as  assistant  engineer  before  any  board  you  happen  to 
go  against.  I  have  been  making  inquiries  to  find  out  just 
what  branches  you  ought  to  be  drilled  on  to  pass  the  exami- 
nation, and  I  find  that  the  law  actually  requires  only  two  sub- 
jects, and  that  is  how  to  make  calculations  concerning  a  lever 
safety-valve  and  how  to  figure  out  the  staying  of  the  flat 
surfaces  of  a  boiler.  Of  course,  no  man  can  be  an  engineer 
who  understands  only  those  problems,  and  you  will  find  that 
before  you  ever  get  your  'ticket'  you  will  have  to  get  a  good 
general  idea  of  the  whole  subject,  as  these  local  boards  are 
very  thorough.  These  examinations  won't  be  like  the  old 
stories  they  tell  about  the  examinations  held  in  the  early  days 
of  the  civil  service,  for  example,  of  how  a  candidate  for  a 
job  in  the  Custom  House  was  asked,  'How  many  Hessians 
came  over  here  during  the  Revolutionary  War?'  Not  know- 
ing definitely,  he  answered,  'A  d n  sight  more  than  went 

back,'  and,  as  the  story  goes,  he  got  the  job.  Another  one  was 
the  candidate  for  the  position  of  letter  carrier,  who,  when 
asked,  'How  many  miles  from  the  earth  to  thetmoon  ?'  replied, 
'If  I  have  to  deliver  letters  there  I  don't  want  the  job.'  " 

"You  will  find  that  the  questions  which  the  steamboat  in- 
spectors ask  you  to  answer  will  be  only  such  as  you  must 
know  to  make  successful  marine  engineers." 

"I  therefore  propose  to  post  you  in  a  general  way  on  the 
principal  things  a  seagoing  engineer  ought  to  know.  I  take 
it  for  granted  that  all  of  you  know  enough  about  arithmetic 
to  make  ordinary  calculations,  so  we  will  not  waste  any  time 
in  going  over  that  subject,  as  you  will  get  enough  practice  in 
it  as  we  go  along  on  the  other  subjects." 

"At  the  start,  I  will  insist  on  each  of  you  getting  a  thorough 


MC  ANDREWS  FLOATING  SCHOOL 


understanding  of  a  few  of  the  elementary  definitions  in  what 
is  known  as  mechanics,  as  no  one  connected  in  any  way  with 
engineering  in  any  of  its  branches  can  make  a  success  of  it 
unless  he  does  understand  these  underlying  facts." 


CHAPTER   III 
Force,  Work  and  Power 

"Come  on,  boys,  let's  turn  to  and  get  right  at  this  business," 
said  McAndrew  to  his  class,  as  they  assembled  on  the  follow- 
ing night.  "The  first  part  of  this  course  is  going  to  be  what 
you  all  need  the  most — a  little  instruction  in  elementary  princi- 
ples. -  There  is  no  good  of  a  man  trying  to  put  a  roof  on  his 
house  until  he  has  at  least  a  pretty  fair  foundation  under  it. 
As  I  have  already  told  you,  I  don't  want  to  go  into  any  'high- 
brow' theories  with  you,  as  both  of  us  would  be  losing  some- 
thing valuable — I'd  lose  my  time  and  you  would  lose  your 
interest. 

"In  all  branches  of  engineering  the  principal  output  is 
power  in  one  form  or  another.  Now,  it  is  a  safe  bet  that  none 
of  you  knows  exactly  what  power  is.  I  want  to  get  the  right 
idea  of  it  firmly  impressed  on  your  memory,  so  that  you  will 
not  be  like  a  certain  Irishman  I  know  of  who,  through  politi- 
cal influence,  got  a  job  to  run  a  small  steam  engine  in  the 
Capitol.  A  sightseer  stopped  to  look  at  his  engine  one  day, 
and  asked  the  son  of  Erin  what  horsepower  it  was.  'Horse- 
power!' he  ejaculated,  'horsepower  be ;  don't  you  see  that 

it  runs  be  stame/ 

"Now  to  understand  what  constitutes  power  you  must  con- 
sider three  elements — force,  distance  and  time.  For  instance, 
here  is  a  block  of  iron  which  weighs  5  pounds.  I  lift  it -up 
I  foot  from  the  deck  by  using  force  to  overcome  its  weight, 


i8  MC  ANDREW'S  FLOATING  SCHOOL 

and  in  so  doing  I  have  performed  work,  which  is  measured 
in  what  is  known  as  foot-pounds;  that  is,  I  have  performed 
5  foot-pounds  of  work  by  overcoming  the  weight  of  this 
5-pound  block  through  a  distance  of  i  foot.  Now  get  that 
fixed  in  your  mind,  force  is  overcoming  weight,  and  work 
is  overcoming  weight  through  distance  or  space.  Now  it 
wouldn't  make  any  difference  whether  I  lifted  that  5-pound 
weight  a  foot  high  in  a  second  or  ten  minutes  so  far  as  the 
term  'work'  is  concerned,  but  when  you  come  to  'power'  then 
there  is  another  thing  to  be  considered,  and  that  is  the  time  it 
takes  to  perform  the  work.  In  measuring  anything  you  must 
have  a  standard  upon  which  to  base  your  measurements; 
thus  you  buy  waste  by  the  pound,  oil  by  the  gallon,  etc.,  so 
the  early  engineers  in  looking  for  a  standard  on  which  to 
measure  power  quite  naturally  selected  the  horse,  that  faith- 
ful beast  which  carries  or  pulls  all  manner  of  burdens  for 
mankind.  As  a  result  of  experiments  on  a  large  number  of 
horses  in  England  many  years  ago,  it  was  decided  that  at  an 
average  a  horse  could  perform  33,000  foot-pounds  of  work 
in  one  minute;  hence  this  was  fixed  as  the  now  almost  uni- 
versally adopted  standard  'horsepower'  for  all  engines.  Al- 
ways keep  in  mind,  therefore,  that  power  consists  of  three 
things — force,  distance  and  time.  Later  on  I'll  show  you  how 
to  calculate  the  horsepower  of  an  engine. 

"The  next  foundation  stone  I  want  you  to  lay  is  to  get  the 
right  idea  of  the  so-called  mechanical  powers.  Only  the  other 
day  I  heard  Nelson  say  when  he  was  working  that  small  jack- 
screw,  'Gee !  but  this  is  a  powerful  little  beggar.'  Don't  forget 
one  thing  right  at  the  start ;  there  never  has  been  any  kind  of 
a  machine  invented  where  you  can  get  more  power  out  of  it 
than  you  put  in  it.  In  fact,  it  is  always  a  little  less  on  ac- 
count of  the  loss  by  friction.  If  that  jack-screw  appeared  to 
lift  a  weight  of  several  tons  with  comparative  ease,  you  must 
remember  that  it  only  lifted  it  a  few  inches,  while  your 


FORCE,   WORK    AND   POWER  IQ 

hand  traveled  a  good  many  feet  in  working  the  bar.  The 
fundamental  principle  of  all  the  mechanical  powers  is  that  the 
weight,  multiplied  by  the  distance  it  moves  through,  is  always 
equal  to  the  force  multiplied  by  the  distance  it  moves  through. 
Suppose  we  take  this  foot-rule  and  put  it  over  a  knife-edge  on 
the  4-inch  mark.  On  the  short  end  we  will  put  these  two 
i-inch  nuts  and  on  the  long  end  we  will  put  one  such  nut,  and 
you  see  that  they  balance  exactly.  Why?  Simply  because 
2X4=1X8  =  8.  That  is  the  principle  of  the  lever,  and 
later  on  you  will  find  that  it  is  the  principle  of  the  lever  safety 
valve  about  which  you  will  have  to  know  before  you  can  ever 
get  your  'ticket'  from  the  steamboat  inspector. 

"The  next  thing  you  want  to  understand  is  the  inclined 
plane.  Suppose  you  want  to  put  a  barrel  of  oil  on  a  truck. 
You  can't  lift  it  off  the  deck,  so  you  go  and  get  a  plank,  and, 
single-handed,  you  can  roll  it  up  and  put  it  in  the  truck.  How 
could  you  do  it?  Simply  because  you  couldn't  lift  it  bodily  a 
distance  of  perhaps  3  feet  you  rolled  it  up  a  plank  10  feet  long. 
In  that  manner,  while  the  barrel  was  lifted  vertically  3  feet, 
you  were  shoving  it  for  a  distance  of  10  feet. 

"A  wedge  is  simply  a  double  inclined  plane;  to  open  up  a 
space  Y2  inch  wide  in  a  plank  you  often  have  to  drive  the 
wedge  lengthwise  eight  or  ten  times  that  distance. 

"The  screw,  such  as' that  jack  I  was  speaking  of,  is  a  com- 
bination of  the  lever  and  the  inclined  plane.  When  you  take 
hold  of  the  end  of  the  bar  and  pull,  it  acts  as  a  lever  on  the 
head  of  the  jack-screw.  The  thread  is  simply  an  inclined 
plane  wrapped  around  the  bolt  Between  the  two  you  can 
exert  a  tremendous  pressure  to  lift  anything,  but  always 
remember  the  great  number  of  times  you  have  to  pull  that  bar 
around,  and  compare  the  distance  your  hand  travels  with  the 
short  distance  the  weight  is  lifted,  then  the  'tremendous  pres- 
sure' exerted  won't  seem  to  be  so  mysterious. 

'There  are  several  other  so-called  mechanical  powers,  but 


2O  MC  ANDREW  S   FLOATING    SCHOOL 

they  are  all  practically  based  on  the  principles  of  the  lever 
and  the  inclined  plane. 

"No  matter  what  tool  or  mechanical  contrivance  you  are 
using,  just  try  to  reason  out  on  the  principles  I  have  given  you 
to-night  how  you  are  accomplishing  the  work.  To-day, 
O'Rourke,  when  you  were  lifting  that  main-bearing  cap,  you 
know  that  you  couldn't  budge  it  alone,  but  you  had  no  trouble 
in  hoisting  it  up  with  the  chain  tackle.  How  do  you  account 
for  that?" 

O'Rourke  scratched  his  head  a  bit  and  said,  "Come  to  think 
of  it  I  guess  I  did  pull  that  chain  about  a  mile  before  I  got 
the  cap  up  a  foot ;  the  next  time  I'll  let  the  Dutchman  'hist' 
her  up,  while  I  take  observations  on  how  far  he  has  to  pull  it." 

"I  see,"  said  McAndrew,  "that  you'll  make  good  as  a  scien- 
tist, as  the  first  thing  any  of  them  learn  is  to  let  some  other 
fellow  do  the  manual  labor." 


CHAPTER  IV 

Heat,   Combustion  and  the  Generation 
of  Steam 

"Having  told  you  something  about  mechanical  powers,  I 
now  propose  to  continue  still  further  my  remarks  on  ele- 
mentary principles,  and  will  take  up  the  subjects  of  heat, 
steam,,  combustion,  etc.  In  starting  off  I  will  ask  you  what 
is  steam?"  As  no  one  else  seemed  to  volunteer  an  answer, 
O'Rourke  blurted  out,  "It's  a  white  gas  that  kills  you  if  you 
breathe  it." 

"It  will  kill  you  all  right,  but  please  remember  that  steam 
is  not  white  until  it  is  condensed  into  small  particles  of  water 
— when  it  is  formed  in  a  boiler  it  is  as  colorless  and  invisible 
as  the  air.  I  am  afraid,  however,  that  your  idea  of  steam  is 
somewhat  cloudy.  Of  course,  you  all  know  that  when  you 
shovel  coal  in  a  furnace,  and  boil  the  water  in  the  boiler, 
steam  is  formed ;  but  how  ?  is  the  question. 

"Heat,  scientific  men  inform  us,  is  a  mode  of  motion.  All 
substances  are  composed  of  infinitesimal  small  particles  called 
molecules.  Heat  is  the  violent  motion  of  these  molecules,  and 
may  be  occasioned  in  two  fundamental  ways.  The  first  is  what 
may  be  termed  chemical  action  or  combustion,  and  that  is  what 
interests  us  most.  The  element  known  as  carbon,  of  which 
coal  is  largely  composed,  unites  with  another  element  known 
as  oxygen,  and  heat  is  generated.  Thus  we  put  coal  contain- 
ing carbon  in  a  furnace  and  admit  air  containing  oxygen 


22  MC  ANDREWS   FLOATING    SCHOOL 

through  the  grate  bars,  and  heat  results  from  the  chemical 
union  of  the  two  elements.  They  must  unite  in  certain  pro- 
portions, so  that  is  the  reason  you  have  to  regulate  the 
dampers  and  ash-pit  doors.  The  right  proportion  is  one  part 
of  carbon  and  two  parts  of  oxygen.  Always  remember  that 
the  air  is  just  as  essential  in  forming  heat  as  is  the  coal." 

"The  air  is  much  easier  shoveling,"  broke  in  O'Rourke.  Not 
paying  any  attention  to  the  interruption,  McAndrew  contin- 
ued:  "The  right  kind  of  a  fireman  is  the  one  who  pays 
attention  to  his  fires  and  allows  the  proper  mixture  of  air  to 
reach  the  fires.  If  you  put  in  too  much  coal,  such  as  the 
'crown-sheeters,'  which  O'Rourke  likes  to  carry,  the  air  does 
not  have  sufficient  chance  to  circulate  through  the  hot  coals 
to  make  good  combustion.  If  the  clinkers  and  ashes  are 
allowed  to  collect  on  the  grates,  they  also  shut  off  the  proper 
amount  of  air  and  your  fires  get  dead.  Hence  the  best  way  to 
make  steam  is  to  carry  a  fire  of  uniform  thickness,  not  more 
than  6  to  8  inches  deep,  and  by  means  of  the  slice-bars  keep 
the  ashes  off  the  grates  as  much  as  possible.  Another  thing 
is  to  keep  your  doors  shut  as  much  as  you  can ;  too  much  air 
is  as  bad  as  too  little.  When  you  have  to  throw  in  coal  do  it 
quickly,  and  spread  it  evenly  over  the  fires.  If  the  conditions 
are  such  that  there  is  one  part  of  the  oxygen  to  one  of  carbon, 
you  will  not  make  much  steam,  as  such  a  mixture  does  not 
burn — simply  smells  bad. 

"As  I  told  you  before,  there  is  a  method  of  measuring  every- 
thing by  comparing  it  with  some  standard.  This  applies  to 
heat  as  much  as  it  does  to  coal  itself,  only  you  do  not  meas- 
ure 'heat  by  its  weight,  as  it  has  none;  therefore  we  must 
measure  it  by  its  effect.  One  of  the  effects  of  applying  heat  to 
metals  is  to  cause  them  to  expand  or  grow  larger.  Taking 
advantage  of  this  quality  the  thermometer  was  invented,  which 
records  the  expansion  and  contraction  of  mercury  in  a  glass 
tube  as  heat  is  applied.  While  the  thermometer  measures  the 


HEAT,   COMBUSTION   AND  THE   GENERATION   OF   STEAM        ,2J 

degree  of  the  heat  in  a  relative  manner  it  does  not  measure 
the  amount.  Hence  a  unit  amount  of  heat  was  decided  to  be 
the  amount  necessary  to  raise  i  pound  of  water  I  degree  on 
the  thermometer.  They  call  that  amount  a  British  thermal 
unit." 

Schmidt  was  very  much  interested  in  this  term  and  re- 
marked, "I  suppose  O'Rourke  would  rather  have  it  called  an 
Irish  unit." 

"Now  it  may  interest  you  to  know  that  a  pound  of  good  coal 
ought  to  produce  something  more  than  13,000  of  these  British 
thermal  units.  Remember  that,  for  by  the  time  you  boys  get 
to  be  chief  engineers  everybody  will  be  buying  coal  by  the 
number  of  British  thermal  units  it  contains  instead  of  specify- 
ing some  particular  brand  of  coal,  as  is  done  now.  If  you  are 
not  buying  coal  you  will  be  buying  fuel  oil ;  but  even  so  you 
will  \vant  to  know  the  thermal  units  it  contains. 

"In  order  not  to  give  you  any  wrong  impressions  as  to  the 
amount  of  air  necessary  for  combustion,  I  want  to  tell  you 
that  for  every  pound  of  average  coal  there  are  needed  about 
two  and  two-thirds  pounds  of  oxygen.  As  the  air  contains 
only  about  one-quarter  of  its  weight  in  oxygen,  it  is  usual  in 
order  to  obtain  a  good  draft  to  admit  about  20  pounds  of  air 
to  the  pound  of  coal.  That  means  that  approximately  250 
cubic  feet  of  air  must  be  admitted  to  the  furnaces  for  every 
pound  of  coal  that  is  burned.  Fortunately,  the  air  costs 
nothing,  or  the  process  of  making  steam  would  be  very  ex~ 
pensive.  Although  I  have  advised  you  to  keep  the  furnace 
doors  open  just  as  briefly  as  possible,  do  not  forget  that  some 
air  must  be  admitted  above  the  fire  in  order  to  attain  proper 
combustion.  In  all  well-designed  furnace  fronts  you  will  find 
a  number  of  holes  for  the  admission  of  air,  so  you  must  see 
that  they  are  kept  open. 

"Now  as  to  the  other  method  of  generating  heat.  All  of 
you  have  noticed  that  if  you  rub  your  hand  briskly  over  a 


24  MC  ANDREWS   FLOATING   SCHOOL 

smooth  piece  of  wood,  for  example,  there  is  a  sensation  of 
warmth.  That  is  due  to  the  energy  you  exert  in  the  rubbing 
process.  If  you  do  not  keep  a  crank-pin  well  oiled  you  know 
that  it  will  soon  become  heated  up,  and  if  it  is  allowed  to  go 
far  enough  it  is  quite  possible  that  sparks  would  fly  or  the 
metal  become  so  heated  as  to  show  color.  This  is  but 
another  example  of  energy  being  transformed  into  heat.  You 
all  know  that  the  heat  from  the  steam  is  quite  readily  turned 
into  power  or  energy  in  the  engine,  so  there  must  be  some 
standard  system  of  comparing  one  with  the  other.  I  have 
already  told  you  that  work  is  measured  in  foot-pounds,  and 
that  heat  is  measured  in  British  thermal  units.  A  scientific 
man  named  Joule  therefore  determined  that  772  foot-pounds 
of  work  was  equivalent  to  a  British  thermal  unit,  and  that  is 
the  way  that  comparisons  are  made.  O'Rourke,  you  are  quite 
a  strong  young  man,  but  you  can  see  that  if  you  hustled  as 
fast  as  possible,  you  would  not  be  able  to  turn  out  as  much 
work  as  even  I  pound  of  coal.  That  shows  you  the  difference 
between  using  your  muscles  and  your  brains.  Coal  is  a  very 
cheap  and  able  competitor  of  the  man  who  •  only  uses  his 
physical  strength,  but  fortunately  for  mankind  brains  can- 
not be  bought  so  cheaply. 

"We  have  seen  how  heat  is  generated  from  coal,  and  you 
must  keep  in  mind  that  heat  is  the  source  of  all  power  for 
marine  propulsion.  Water  is  found  to  be  the  ideal  means  of 
conveyance  for  transforming  the  heat  into  power ;  it  is  easily 
converted  into  steam  and  it  exists  in  great  abundance.  Hence 
the  large  majority  of  marine  engines  are  designed  to  work  by 
steam  generated  from  water.  You  know  that  the  result  of 
starting  fires  hi  a  boiler  containing  water  is  the  generation  of 
steam.  If  you  put  a  thermometer  in  the  boiler  water  you 
would  see  that  some  time  after  the  fires  are  started  the  tem- 
perature would  gradually  rise  until  it  reached  the  boiling  point, 
usually  taken  at  212  degrees  above  zero.  The  heat  thus  ap7 


HEAT,   COMBUSTION    AND   THE  GENERATION   OF   STEAM          2$ 

plied  is  known  as  sensible  heat,  from  the  fact  that  it  is  ap- 
parent to  the  senses.  After  having  reached  that  temperature 
it  takes  considerable  time  until  steam  is  finally  formed.  This 
is  due  to  the  fact  that  for  water  to  be  turned  into  steam  a 
great  amount  of  heat  is  necessary  to  break  up  the  liquid  water 
and  transform  it  into  the  vapor — steam.  The  heat  thus  ab- 
sorbed by  the  water  in  the  transformation  is  known  as  the 
'latent'  heat.  To  bring  about  this  change  there  are  required 
966  British  thermal  units  per  pound  of  water,  while  it  only 
took  152  British  thermal  units  per  pound  of  water  to  raise  it 
from  the  temperature  it  was  put  into  the  boiler,  say  at  60 
degrees,  to  the  boiling  point." 

"Does  this  latent  heat  burn  you  as  much  as  the  other  kind 
of  heat?"  said  Pierce. 

'Try  it  and  see,"  replied  McAndrew.  "If  you  stick  your 
hand  in  water  at  the  boiling  temperature  I  don't  believe  you 
will  care  whether  the  heat  is  'sensible'  or  'latent.' " 

"If  he's  sensible  I  think  he  will  keep  his  hand  out  of  it," 
broke  in  the  irrepressible  O'Rourke. 

"Now,"  continued  the  instructor,  "you  have  sometimes 
heard  the  expression  'saturated'  steam,  and  I  suppose  you 
think  that  something  must  have  been  mixed  with  it;  but  that 
is  not  the  meaning  at  all.  It  really  means  steam  in  its  natural 
condition;  that  is,  for  every  pound  pressure  on  the  boiler 
there  is  a  certain  temperature  corresponding." 

O'Rourke  whispered  to  Schmidt,  "I'm  on ;  now  I  know  why 
they  say  a  man  is  'saturated,'  like  that  drunken  oiler  we  had 
last  trip;  it  was  his  natural  condition  all  right." 

"If  more  heat  is  added  to  the  steam  than  is  due  to  that 
of  its  pressure  then  we  have  what  is  known  as  'superheated' 
steam ;  and  people  are  waking  up  to  the  fact  nowadays,  after 
discarding  the  use  of  superheated  steam  years  ago,  that  there 
is  real  economy  in  it.  I  think  that  before  long  you  will  see 
nearly  all  marine  engines  using  superheated  steam. 


26  MC  ANDREW'S  FLOATING  SCHOOL 

"If  the  steam  was  generated  under  an  atmospheric  pressure 
only,  a  cubic  inch  of  water  would  form  1,663  cubic  inches  of 
steam.  To  memorize  that  fact  keep  in  mind  that  a  cubic  inch 
of  water  will  make  nearly  i  cubic  foot  of  steam.  Don't  follow 
that  rule  too  strictly,  or  some  time  you  may  be  as  badly  off 
as  the  old  lady  who,  when  asked  for  a  pound  of  shot  and  not 
having  any  scales,  remembered  the  old  rule,  'A  pint's  a  pound 
the  world  around/  and  gave  the  purchaser  a  pint  of  shot. 
Right  here  let  me  warn  you  about  using  these  old  approximate 
rules  too  freely  unless  you  really  understand  why  they  are 
used  and  know  the  correct  ones.  Engineering  is  an  exact 
science,  and  it  does  not  pay  to  guess  at  anything. 

"Steam,  however,  is  not  generated  in  boilers  under  atmos- 
pheric pressure;  therefore  I  want  you  to  know  that  while 
water,  will  begin  to  boil  at  a  sensible  heat  of  212  degrees  when 
the  steam  is  unconfined,  as  the  pressure  rises,  the  boiling  point 
is  raised  correspondingly.  Thus  at  20  pounds  pressure  it  will 
not  boil  until  the  temperature  is  228  degrees,  at  50  pounds 
pressure  at  281  degrees,  at  160  pounds  at  363.6  degrees,  and  so 
on.  Perhaps  I  should  tell  you  here  that  the  pressures  I  have 
given  are  what  are  known  as  absolute  pressures,  and  I  sur- 
mise that  you  do  not  know  what  that  term  means.  It  prob- 
ably has  never  occurred  to  you  that  air  weighs  something; 
you  breathe  it  and  move  through  it  as  if  it  did  not  cause  any 
particular  resistance,  but  the  pressure  is  there  just  the  same. 
Now  to  understand  it  you  must  consider  that  the  atmosphere 
we  move  around  in  is  similar  to  water ;  the  deeper  you  go  in 
it  the  greater  is  the  pressure,  but  as  we  are  generally  at  the 
bottom  of  the  air,  which  is  at  the  level  of  the  sea,  we 
usually  have  the  greatest  pressure  attainable,  and  it  amounts 
to  14.7  pounds  per  square  inch.  In  some  foreign  countries 
they  speak  of  the  pressure  on  the  boiler  not  as  so  many  pounds 
per  square  inch  but  as  so  many  'atmospheres.'  Thus  a  pressure 
of  10  atmospheres,  you  can  quite  readily  understand,  is  ten 


HEAT,   COMBUSTION   AND   THE   GENERATION   OF   STEAM          27 

times  14.7  pounds,  or  147  pounds  gage  pressure.  If  you  were 
at  the  top  of  a  high  mountain,  the  air  pressure  would  not  be 
so  great  and  water  would  boil  at  a  less  temperature  than  212 
degrees.  The  steam  gages  on  a  boiler  always  record  the 
pressure  above  the  atmosphere;  hence  to  find  the  absolute 
pressure  of  steam  you  must  add  to  the  apparent  pressure 
shown  on  the  steam  gage  the  constant  14.7.  This  is  important 
for  you  to  remember,  for  later  on  when  we  get  to  talking 
about  pressures  in  triple-expansion  engines  and  turbines  you 
must  forget  about  steam-gage  pressures  and  deal  in  absolute 
pressures." 

"How  is  it,"  asked  Schmidt,  "that  this  atmospheric  pressure 
don't  crush  in  our  ribs?" 

"That's  a  good  question,"  replied  the  Chief,  "and  I'll  answer 
you  by  asking  you  one.  How  is  it  that  a  thin  box  without  a 
lid  on,  sunk  at  the  bottom  in  25  feet  of  water,  is  not  crushed 
by  the  water  pressure?  I'll  also  tell  you  the  answer,  and  that 
is  because  the  water  is  on  both  sides  of  the  walls  of  the  box, 
and  it  is  consequently  balanced.  So  with  the  human  system, 
we  breathe  air  and  get  it  inside  of  us  and  there  is  a  balance. 
Now  if  that  thin  box  had  a  lid  on  it  and  was  watertight  the 
sides  would  be  crushed  by  the  water  pressure." 

"Gee!"  interrupted  O'Rourke,  "I'll  keep  my  lid  off  after 
this !  I  don't  want  my  sides  crushed  in !" 

"No  danger  of  that,"  retorted  Schmidt.  "You  are  not 
watertight— you've  got  a  leak  in -your  throat." 

"Following  this  discussion  on  the  pressure  of  air,  we  might 
as  well  take  up  the  question  of  Vacuum'  and  get  a  good  idea 
of  that.  O'Rourke,  what  do  you  understand  is  meant  by 
a  'vacuum'?" 

"Why— er— let  me  see,"  replied  the  talkative  one.  "Why— 
er— it's  something  in  the  condenser  that  sucks  in  your  hand  if 
you  put  it  over  the  air  cock." 

McAndrew  smiled  and  said,  "No;  it  is  something  that  is 


28  MC  ANDREW'S  FLOATING  SCHOOL 

not  in  the  condenser,  and  your  hand  is  not  'sucked  in'  but 
forced  in  by  the  pressure  outside ;  otherwise,  O'Rourke,  your 
answer  is  excellent.  You  made  two  guesses  and  got  them 
both  wrong.  You  might  have  gone  further  in  your  lucid 
description  and  said  that  it  was  something  which  smelled  bad. 
The  term  vacuum  really  means  the  absence  of  air,  or  the 
absolute  zero  of  pressure.  I  have  just  told  you  that  the  air 
under  normal  conditions,  at  the  level  of  the  sea,  weighs  14.7 
pounds  per  square  inch.  Now  if  you  pump  out  all  the  air  from 
a  box  or  other  receptacle  there  is  no  pressure  in  it  because 
there  is  no  air.  If  a  small  amount  of  air  is  allowed  to  rush 
in  there  will  be,  naturally,  a  small  pressure,  but  how  much? 
That  is  what  we  want  to  know,  as  there  must  be  some  means 
of  measuring  it.  You  all  have  learned  undoubtedly  that  this 
ship  carries  26  inches  of  vacuum  when  we  are  running.  That 
comes  from  the  fact  that  some  early  scientific  fellow  learned 
by  experiment  that  the  pressure  of  the  atmosphere  (14.7 
pounds  per  square  inch)  was  the  same  as  the  weight  of  a 
column  of  mercury,  or  quicksilver,  as  you  may  know  it,  29.74 
inches  in  height.  In  other  words,  a  perfect  vacuum,  or  the 
absence  of  all  air  in  a  condenser,  would  be  shown  on  the 
vacuum  gage  as  29.74  inches.  If  a  small  amount  of  air  be 
admitted  the  needle  on  the  gage  would  show  a  vacuum  of 
less  than  that,  as  the  balance  between  the  air  and  the  mercury 
would  be  disturbed.  Finally,  if  the  condenser  was  opened  so 
that  air  could  rush  in  freely,  the  needle  would  go  back  to  the 
zero  mark.  It  is  customary,  therefore,  to  speak  of  carrying  a 
vacuum  of  so  many  inches,  but  don't  ever  speak  of  having  a 
vacuum  of  over  30  inches,  or  people  will  think  you  are  foolish. 
As  a  matter  of  fact,  it  is  quite  difficult  on  ordinary  ships  to 
get  a  vacuum  much  over  28  or  28;^  inches.  As  2  inches  of 
vacuum  is  equivalent  to  I  pound  of  pressure  you  can  see  how 
valuable  it  is  for  the  working  of  the  engine  to  have  as  great  a 
vacuum  as  possible. 


HEAT,  COMBUSTION   AND  THE  GENERATION   OF   STEAM  2Q 

"While  on  the  subject  of  vacuum,  it  will  be  well  for  us  to 
take  up  the  subject  of  how  far  a  pump  will  lift  water.  After 
all  this  is  very  simple,  as  the  pump  does  not  lift  the  water  at 
all;  it  simply  pumps  out  the  air,  and  the  air  pressure  from 
without  forces  the  water  up  the  suction  pipe.  On  the  same 
principle  as  the  column  of  mercury,  it  has  been  determined 
that  the  unit  weight  of  air  (the  atmospheric  pressure)  will 
sustain  the  weight  of  a  column  of  water  about  33.5  feet  in 
height,  and  that  is  the  maximum  height  that  water  can  be 
lifted  by  a  pump,  so  never  try  to  pump  water  through  a  suction 
pipe  any  higher  than  that.  You  can  force  it  to  almost  any 
height  necessary,  but  you  can't  lift  it  any  higher  than  33.5  feet. 
There  is  an  old  saying  that  'Nature  abhors  a  vacuum."  It  is 
not  sp  much  an  abhorrence  as  it  is  the  universal  tendency  of 
Nature  to  maintain  things  in  an  equilibrium  or  balance.  If 
you  disturb  this  balance  by  removing  the  air  from  anything, 
the  outside  air,  water  or  whatever  medium  it  is,  will  rush  in  to 
restore  the  equilibrium." 

Just  then,  Pierce,  who  had  been  leaning  back  in  his  chair, 
intensely  interested  in  what  was  being  said,  fell  over  back- 
wards, much  to  the  amusement  of  O'Rourke,  who  remarked, 
'There  she  goes  again ;  Nature  is  restoring  his  balance !" 


CHAPTER   V 

Engineering  Materials 

McAndrew,  feeling  somewhat  encouraged  at  the  interest 
which  his  class  had  shown  during  his  remarks  on  elementary 
principles,  decided  that  the  next  step  in  order  would  be  to 
give  them  an  idea  of  engineering  materials,  so  he  opened  his 
remarks  by  saying:  "Boys,  what  material  is  a  cold  chisel  made 
from  ?"  Three  of  them  answered  promptly,  "Steel,  sir/' 
O'Rourke  dissented  somewhat  by  saying  that  he  thought  the 
one  he  had  been  using  that  day  must  have  been  made  of  lead, 
as  he  had  to  grind  it  so  often.  Paying  no  attention  to  the 
sally,  the  engineer  pedagogue  said :  "Well,  what  is  the  differ- 
ence between  steel  and  iron?"  As  a  deep  silence  followed  the 
question,  he  remarked :  "I  thought  you  didn't  know,  and  that's 
the  reason  I  asked  you.  Since  you  have,  I  hope,  absorbed  a 
few  ideas  about  elementary  principles  in  engineering,  I  want 
to  drill  into  you  some  idea  of  the  materials  used  in  building 
marine  machinery. 

"The  first  and  most  important  of  them  is  iron,  man's  most 
valuable  metal."  "What  about  gold,  sir?"  interjected 
O'Rourke.  "I'm  glad  you  spoke  about  that,  as  it  shows  that 
you  think  what  most  other  people  do.  As  a  matter  of  fact, 
we  could  get  along  very  well  without  gold,  but  we  would  have 
hard  sledding  to  get  along  without  iron.  Gold  is  only  valuable 
because  of  its  scarcity,  while  iron  is  valuable  on  account  of 
its  usefulness.  Luckily,  it  is  found  in  great  quantities  in 


ENGINEERING    MATERIALS  3! 

almost  all  parts  of  the  world,  and  as  it  would  be  practically 
impossible  to  build  marine  machinery  without  it,  we  will 
try  and  see  what  cast  iron  really  is. 

"Since  the  days  of  old  Tubal  Cain,  iron  has  been  mined  and 
utilized  by  mankind  for  all  kinds  of  implements.  It  exists 
in  a  number  of  different  combinations  known  as  ores,  some 
containing  as  high  as  75  percent  of  pure  iron.  The  first 
process  after  it  is  taken  from  the  ground  is  to  separate  the 
iron  from  the  other  substances,  and  this  is  done  in  what 
are  known  as  blast  furnaces.  The  scheme  is  to  mix  the  iron 
ore  with  coal  or  other  fuel  and  melt  the  whole  mass  down  by 
means  of  forced  combustion  of  the  coal,  hence  the  term  'blast 
furnace.'  The  molten  iron  being  heavier  than  the  other  sub- 
stances, is  drawn  off  at  the  bottom  of  the  furnace,  and  being 
liquid  is  run  along  channels  in  a  bed  of  sand,  known  as  the 
pig  bed,  into  depressions  or  molds  in  the  sand  about  3^2  feet 
long,  6  inches  wide  and  4  or  5  inches  deep.  When  these  are 
cold  they  are  known  as  'pigs,'  and  thus  we  have  the  raw  mate- 
rial known  as  pig  iron. 

"Pig  iron,  of  course,  varies  in  quality,  as  it  is  affected 
largely  by  the  impurities  of  the  coal,  such  as  sulphur,  silicon, 
etc.,  which  get  mixed  with  it  during  the  melting  process. 
In  olden  days,  before  wood  became  so  scarce,  and  there  were 
no  Pinchots  to  say  'Woodman,  spare  that  tree,'  iron  ore  was 
melted  down  with  charcoal,  and  consequently  not  so  many 
impurities  entered  into  the  pig  iron.  That  metal  was  then 
known  as  charcoal  iron,  and  you  can  yet  hear  old  timers 
bemoan  the  fact  that  they  get  so  little  of  it  these  days. 
And  it  is  a  fact  that  genuine  charcoal  iron  is  now  very  scarce 
indeed.  However,  we  get  along  quite  well  without  it  by  hav- 
ing learned  to  make  steel  better  and  cheaper  than  the  pioneers 
could. 

"Now  that  you  know  something  about  cast  iron,  we  will 
see  for  what  purposes  it  is  used  on  board  ship.  You  all 


32  MC  ANDREW  S   FLOATING   SCHOOL 

probably  know  that  the  cylinders  are  made  of  cast  iron, 
always  have  been  and  always  will  be,  as  it  cannot  be  improved 
upon  for  the  purpose.  It  has  sufficient  strength  to  withstand 
the  strain,  will  not  melt  or  change  under  the  heat,  is  readily 
machined,  can  be  made  into  almost  any  form,  becomes  very 
smooth  on  wearing  surfaces,  and,  above  all,  is  very  reason- 
able in  price.  That  combination  of  qualities  can  never  be 
excelled  by  any  known  metal." 

"How  strong  is  cast  iron?"  said  Pierce. 

"That's  a  good  question,"  was  the  reply.  "As  I  told  you 
before,  everything  to  be  measured  must  have  some  standard 
of  comparison.  In  the  case  of  cast  iron,  the  usual  standard 
is  what  is  known  as  its  tensile  strength  per  square  inch.  That 
means  the  number  of  pounds  it  would  take  to  pull  a  bar 
one  inch  square,  or  one  square  inch  in  section,  until  it  breaks. 
It  is  placed  in  a  testing  machine,  which  works  very  much  on 
the  principle  of  a  beam  weighing  machine,  and  the  weight 
or  strain  is  gradually  applied  until  the  test  piece  breaks  in 
two.  The  strength  of  the  metal  varies  according  to  its  quality 
and  treatment,  and  its  quality  usually  depends  on  the  amount 
of  impurities  contained  in  the  metal. 

"First-class  iron,  such  as  used  in  cylinders,  frequently  has 
a  tensile  strength  between  25,000  and  30,000  pounds  per  square 
inch.  Other  and  poorer  grades,  such  as  are  used  in  grate 
bars,  furnace  fittings,  etc.,  have  a  strength  of  only  10,000  to 
15,000  pounds  to  the  square  inch. 

"Rigidity  is  the  main  feature  of  cast  iron,  and  other  tests, 
such  as  crushing  and  bending,  are  given  to  it,  yet  for  all  prac- 
tical purposes  the  marine  engineer  is  satisfied  to  know  that  it 
has  the  required  tensile  strength,  as  that  is  generally  a  guar- 
antee that  it  will  withstand  any  crushing  or  bending  strains 
that  will  be  placed  upon  it. 

"Bedplates  and  condenser  shells  or  walls  are  made  of  cast 
iron  of  fairly  good  quality,  but  need  not  be  of  such  good 


ENGINEERING    MATERIALS  33 

material  as  that  used  for  the  cylinders.  Guides,  pistons,  etc., 
are  usually  made  of  the  best  quality  of  iron. 

"What  is  wrought  iron,  did  you  say  ?  That's  something  you 
hear  about,  but  very  seldom  see  these  days.  Strictly  speaking, 
wrought  iron  is  literally  pure  iron,  or  iron  with  all  other 
ingredients  removed.  Before  we  knew  so  much  about  steel 
making  there  were  large  quantities  of  wrought  iron  used  about 
a  ship;  in  fact,  the  ship's  hull  itself  was  built  of  it.  The 
process  of  making  it  was  to  melt  cast  iron  in  what  was  known 
as  a  reverberatory  furnace — that  is,  a  furnace  where  the  iron 
came  in  contact  with  the  flame  but  not  the  fuel.  By  this 
means  the  carbon,  etc.,  was  burned  out  of  the  molten  mass  as 
well  as  could  be,  and  men  called  puddlers  stuck  a  bar  into 
the  boiling  iron,  rolled  up  a  ball  of  it,  like  you  would  taffy, 
put  it  under  a  squeezer  or  hammer  to  squeeze  out  the  dro.ss, 
then  either  hammered  or  rolled  it  out  into  bars  or  sheets. 
This  material  could  be  forged,  welded  or  rolled  into  almost 
any  shape  desired.  The  process  of  its  manufacture  was  slow 
and  expensive,  and  it  has  now  been  practically  abandoned. 

"Before  I  go  any  further  I  want  to  impress  upon  you  the 
main  distinction  between  cast  iron,  wrought  iron  and  steel. 
Remember  these  fundamental  facts  and  you  will  have  the 
general  idea: 

"i.  Wrought  iron  is  pure  iron  with  very  little  or  no  carbon 
in  it. 

"2.  Steel  is  pure  iron  mixed  with  from  one-tenth  of  one  per- 
cent to  sometimes  one  and  two-tenths  percent  of  carbon,  ac- 
cording to  the  grade  of  steel  required. 

"3.  Cast  iron  is  iron  mixed  with  about  31A  percent  of  carbon, 
and  with  certain  combinations  even  a  higher  percentage  than 
that. 

"You  will  thus  see  that  the  main  distinction  between  these 
different  grades  of  material  is  the  amount  of  carbon  they  con- 
tain. To  be  sure,  there  are  other  ingredients  in  the  mixture, 


34  MC  ANDREW'S  FLOATING  SCHOOL 

such  as  sulphur,  manganese  and  silicon  in  varying  quantities. 
Sulphur  is  always  bad,  but  certain  small  amounts  of  man- 
ganese and  silicon  are  beneficial." 

"What  is  this  malleable  iron  we  hear  about?"  inquired 
Pierce  of  the  instructor. 

"Malleable,"  replied  McAndrew,  "means  capable  of  being 
hammered  or  rolled  into  shape,  and  although  it  sounds  very 
good  when  applied  to  cast  iron,  you  don't  want  to  hammer  it 
too  vigorously  or  you  will  find  that  it  will  take  the  shape  of 
two  or  three  separate  pieces,  such  as  that  two-inch  elbow  I 
saw  O'Rourke  wrestling  with  this  afternoon." 

"I  didn't  think  you  was  looking  when  I  busted  that  elbow," 
replied  the  guilty  one. 

"I  saw  it  all  right,  and  let  that  be  a  lesson  to  you  that  all 
malleable  iron  is  not  as  'malleable'  as  you  might  imagine. 

"In  making  iron  castings  malleable,  they  are  packed  in 
some  substance,  such  as  mill  scale  or  sand  which  will  not 
melt,  heated  to  red  heat  and  allowed  to  stand  for  a  number 
of  days,  during  which  time  some  of  the  carbon  is  withdrawn 
from  the  surface  of  the  castings,  which  to  a  certain  extent 
makes  them  tougher  and  more  ductile.  This  process  is  used 
principally  for  small  castings,  such  as  pipe  fittings.  Some 
people  claim  that  malleable  iron  can  be  welded ;  so,  to  demon- 
strate whether  that  claim  is  true  or  not,  I'll  have  O'Rourke 
weld  up  that  elbow  he  broke." 

"Gee!  I  wish  you  would  let  me  buy  a  new  one  instead," 
pleaded  the  Irish  lad.  "I'm  not  much  on  this  scientific  dope." 

"To  return  to  the  subject,"  said  McAndrew,  "we  will  next 
take  up  the  subject  of  steel,  as  used  for  shipbuilding. 

"There  are  two  principal  processes  used  in  the  manufacture 
of  structural  steel,  the  Bessemer  and  open-hearth.  As  Bes- 
semer steel  is  not  used  in  any  part  of  a  ship,  it  will  suffice  to 
discuss  the  open-hearth  process. 

"This  consists  essentially  of  melting  pig  iron,  scrap  steel  and 


ENGINEERING    MATERIALS  35 

wrought  iron  in  a  large  circular  furnace,  sometimes  as  large 
as  20  feet  in  diameter,  the  heat  being  furnished  by  the  com- 
bustion of  gas  over  the  top  of  the  metal,  so  that,  unlike  a 
blast  furnace,  the  fuel  does  not  come  in  contact  with  the 
metal.  This  results  in  burning  out  the  carbon  in  the  mixture 
to  a  degree  slightly  less  than  that  required  in  the  steel  to  be 
made.  In  order  to  get  the  exact  proportion  of  carbon  re- 
quired in  the  mixture,  a  certain  amount  of  'spiegel-eisen'  is 
added." 

"What's  that,  sir?"  inquired  O'Rourke. 

"Ask  your  German  friend,"  replied  McAndrew. 

"I  don't  know  just  what  'spiegel-eisen'  is,"  replied  Schmidt, 
"but  in  German  it  means  looking-glass  iron." 

"That's  right,"  said  the  instructor.  "It  gets  its  name  from 
its  bright  surface,  and  it  is  really  an  iron  ore  containing  a 
large  proportion  of  manganese.  This  manganese  unites  with 
the  oxygen  and  sulphur  in  the  mixture  and  removes  them. 
Spiegel-eisen  also  adds  the  requisite  amount  of  carbon  to  the 
mixture.  After  it  is  determined  by  the  man  in  charge  of 
the  furnace  that  the  desired  mixture  is  reached,  the  molten 
steel  is  run  into  ladles,  from  which  it  is  poured  into  large 
molds  which  shape  the  metal  into  huge  blocks  of  steel  known 
as  ingots.  These  ingots  are,  when  needed,  heated  in  a  fiery 
retort  to  almost  a  white  heat,  and  run  back  and  forth  through 
rolls  until  they  are  shaped  into  what  are  known  technically  as 
slabs  and  billets.  In  that  shape  they  are  selected  to  fill  orders 
for  boiler  or  ship  plates  and  engine  forgings,  such  as  shafting, 
piston  and  connecting  rods,  columns,  valve  stems,  etc." 

"How  can  you  tell  this  open-hearth  steel  from  wrought 
iron?"  inquired  Nelson. 

"Easy  enough,"  interjected  O'Rourke,  "ask  the  man  you  buy 
it  from!" 

"That  would  be  all  right,"  said  McAndrew,  "if  he  knew  the 
difference  himself.  As  a  matter  of  fact,  it  is  very  difficult 


36  MC  ANDREW'S  FLOATING  SCHOOL 

to  tell  from  appearances.  Some  people  claim  that  they  can 
tell  by  looking  at  it,  but  I  have  my  doubts  as  to  that.  Others 
who  are  expert  in  working  iron  and  steel  can  be  reasonably 
sure  by  the  way  they  cut.  I  remember  once  of  being  in  doubt 
whether  a  certain  lot  of  boiler  tubes  were  of  wrought  iron 
or  mild  steel,  and  I  could  find  no  one  who  was  absolutely 
sure  as  to  the  material  of  which  they  were  made.  There  is 
one  infallible  way,  however,  of  telling,  and  that  is  by  cutting 
the  metal  in  two,  polishing  up  the  surface  and  pouring  on  a 
little  nitric  acid.  In  wrought  iron  there  is  bound  to  be  a 
certain  amount  of  slag  in  the  mixture  which  strings  out  in 
the  rolling  process  and  gives  the  metal  the  appearance  of  hav- 
ing a  grain.  When  nitric  acid  is  applied,  the  pure  iron  is  eaten 
away  and  leaves  the  grain  sticking  above  the  surface.  Steel 
being  practically  a  homogeneous  metal  is  eaten  away  uni- 
formly by  the  acid. 

"The  next  most  important  metal  for  marine  machinery  is 
brass,  and  I'll  ask  O'Rourke  to  tell  you  what  it  is." 

Clearing  his  throat  and  assuming  an  air  of  importance  at 
being  called  upon  for  an  expert  opinion,  the  son  of  Erin 
replied:  "Brass  is  a  metal  that  is  mined — I  don't  know  jnst 
where ;  it  costs  like  blazes,  smells  bad,  is  'pisonous'  to  the  skin, 
gets  dirty  in  five  minutes,  and  is  used  around  an  engine  room 
principally  for  the  purpose  of  keeping  the  poor  firemen  busy 
shining  it  up  when  they  ought  to  be  resting  themselves." 

"That  certainly  is  a  very  lucid  description,  and  coming  from 
such  an  expert  on  'brass'  it  will  have  great  weight.  How- 
ever, I  cannot  agree  with  all  your  conclusions,  and  especially 
as  to  its  being  mined. 

"Brass,  as  it  is  commonly  termed,  is  not  an  elementary 
metal,  as  it  is  composed  of  two  and  sometimes  three  ele- 
ments, such  combinations  of  two  or  more  metals  being  known 
generally  as  alloys.  An  alloy  composed  of  copper  and  zinc,  or 


ENGINEERING    MATERIALS  37 

of  copper,  zinc  and  a  very  small  amount  of  tin,  is  known  as 
brass.  When  a  larger  proportion  of  tin  or  other  metal,  such 
as  aluminum  or  lead,  is  used,  the  alloy  is  known  as  a  bronze. 
As  a  matter  of  fact,  the  terms  'gun  metal,'  'composition,'  and 
'bronze'  are  used  rather  loosely,  and  it  is  hard  to  draw  a  line 
of  demarcation  between  them. 

"The  principal  reasons  for  using  brass,  composition,  bronze, 
etc.,  in  the  construction  of  marine  machinery  are  their  de- 
creased friction  when  rubbed  on  other  metals,  their  freedom 
from  oxidization  or  corrosion,  as  it  is  commonly  called,  and 
in  some  instances  for  ornamentation.  The  latter  reason  is 
growing  less  every  day,  as  there  is  plenty  of  other  work  on 
board  a  modern  vessel  to  keep  the  firemen  busy  without  having 
needless  brasswork  to  polish. 

''There  are  about  a  million  different  compositions  of  cop- 
per, tin,  zinc,  lead,  antimony,  iron,  aluminum,  etc.,  which  can 
be  made,  but  the  principal  ones  of  interest  to  marine  engi- 
neers are  the  following,  mixed  in  the  proportions  given: 

"Common  yellow  brass:  Copper,  65.3;  zinc,  32.7;  lead,  2. 

"Babbit  metal:  Copper,  3.7;  tin,  88.9;  antimony,  7.4. 

"Brazing  metal:  Copper,  84;  zinc,  16. 

"Admiralty  bronze:  Copper,  87;  tin,  8;  zinc,  5. 

"Manganese  bronze:  Copper,  88.64;  tin,  8.7;  zinc,  1.57;  iron, 
.72 ;  lead,  .30. 

"Muntz  metal:  Copper,  60;  zinc,  40. 

"Navy  composition:  Copper,  88;  tin,  10;  zinc,  2. 

"White  metal:  Lead,  88;  antimony,  12. 

"Phosphor  bronze:  Copper,  90  to  92;  phosphide  of  tin,  10 
to  8. 

"Tobin  bronze :  Copper,  59  to  61 ;  tin,  I  to  2 ;  zinc,  37  to  38 ; 
iron,  .1  to  .2;  antimony,  .3  to  .35. 

"You  probably  will  never  be  called  upon  to  mix  any  of 
Ihese  compositions  yourselves,  and  it  is  well  that  you  will  "not, 


38 

as  it  takes  an  expert  to  do  it.  However,  it  will  do  you  no 
harm  to  know  what  goes  into  the  various  metals  with  which 
you  will  have  to  deal. 

"There  is  another  alloy  which  is  rapidly  coming  in  use  for 
marine  machinery,  known  as  'Monel  metal.'  Unlike  other 
compositions,  it  is  mixed  by  Nature  itself,  as  it  is  in  reality 
nickel  ore  just  as  it  is  mined.  It  is  composed  principally  of 
nickel  and  copper  in  about  the  proportion  of  65  to  35.  It 
has  been  found  to  be  very  efficient  for  valve  seats  in  steam 
valves  where  superheated  steam  is  used,  for  pump  rods  and 
valve  stems,  and  for  propellers.  The  tensile  strength  is 
equal  to  that  of  steel,  and  it  is  non-corrosive  in  salt  water 
and  acids. 

"I  have  now  described  to  you  in  a  general  way  the  prin- 
cipal materials  used  in  an  engine  room " 

"You  have  left  the  main  ones  out,  Chief !"  said  O'Rourke. 

"What  are  they?" 

"Why,  the  gold  and  silver  that  are  handed  out  once  a 
month." 

"You'll  have  to  know  a  good  deal  more  about  steel  and 
brass  than  you  do  now  before  you  can  connect  very  strongly 
with  those  metals,"  retorted  McAndrew,  as  he  dismissed  the 
class  for  the  evening. 


CHAPTER  VI 

Boilers 

"We  have  now  covered  the  most  important  of  the  funda- 
mental subjects  which  all  engineers  should  know,  so  we  will 
begin  on  the  subjects  relating  to  the  parts  you  are  most  in- 
terested in,  that  is,  those  with  which  you  have  already  had 
some  practice.  I  will  therefore  ask  you  what,  in  the  opinion 
of  each,  is  the  most  important  thing  to  take  up." 

"Propellers,"  promptly  replied  Pierce;  "they  drive  the 
ships." 

"No,  sir,"  said  Schmidt,  "let's  take  up  the  engines,  for  they 
drive  the  propellers." 

"I  think  we  ought  to  begin  with  boilers,  sir,"  remarked 
Nelson ;  "they  furnish  the  steam  which  drives  the  engines." 

"Ah!"  said  O'Rourke,  "if  that's  the  reason,  let's  take  up 
'the  walking  of  the  ghost'  when  he  comes  across  with  the 
money  that  makes  'em  all  go." 

"Nelson,"  said  McAndrew,  "has  the  right  idea — the  boilers 
are  the  most  important  parts  of  marine  steam  machinery.  If 
you  don't  get  the  steam  first,  no  matter  how  good  the  engines 
and  propellers  may  be,  the  ship  will  not  move. 

"I  have  already  told  you  what  happened  when  coal  is  put 
in  the  furnaces,  and  now  we  want  to  know  something  about 
the  boilers  that  hold  the  steam  after  it  is  made.  How  many 
kinds  of  boilers  are  there,  O'Rourke?" 

"Two,  sir,"  replied  that  youngster;  "tight  ones  and  leaky 
ones." 


40  MC  ANDREW'S  FLOATING  SCHOOL 

"Well,  that's  a  good  distinction,  but  hardly  the  kind  that 
we  want  to  talk  about,  although  I'll  admit  that  a  tight  boiler 
of  any  description  is  better  than  any  kind  that  leaks.  If  you 
were  to  study  books  on  the  subject  you  would  have  to  read 
descriptions  of  a  dozen  types  of  shell  boilers,  but  as  there  is 
practically  only  one  type  used  on  steamers  nowadays,  any 
knowledge  you  might  gain  about  discarded  types  would  be  as 
useful  to  you  as  last  year's  bird  nests.  The  principal  type  of 
shell  boiler  all  marine  engineers  in  the  merchant  service  have 
to  deal  with  now  is  the  Scotch  type — single  or  double-ended. 
By  the  time  you  boys  get  to  be  chief  engineers  even  that 
type  will  probably  be  put  on  the  shelf,  as  the  day  of  the  use 
of  watertube  boilers  is  fast  approaching.  However,  as  the 
Scotch  boiler  is  just  at  present  the  principal  one  to  be  con- 
sidered, we  will  give  that  first  attention.  This  boiler  is  named, 
probably,  from  the  fact  that  it  was  first  developed  by  Scotch 
shipbuilders,  than  whom,"  said  McAndrew,  .evidently  taking 
pride  in  his  ancestry,  "there  are  no  better  in  the  world. 

"Up  to  the  present  time  it  has  stood  the  test  of  service 
better  than  any  others  of  the  class  of  shell  boilers,  and  has 
consequently  lived  to  see  the  others  discarded.  Theoretically, 
an  ideal  shell  boiler,  to  withstand  internal  pressure,  would  be 
one  shaped  like  a  sphere  or  ball,  as  curved  surfaces  need  no 
bracing;  flat  surfaces  should  be  avoided  in  boiler  work,  and 
the  principal  feature  of  a  Scotch  boiler,  which  makes  it  so 
efficient,  is  that  there  are  as  few  flat  surfaces  as  possible. 
The  shell  of  the  boiler  is  made  cylindrical,  the  furnaces  are 
cylindrical,  as  also,  of  course,  are  the  tubes.  Consequently, 
the  only  flat  surfaces  are  the  heads  and  portions  of  the  com- 
oustion  chambers. 

"The  thickness  of  the  boiler  shell  depends  upon  three 
ihings:  the  steam  pressure  to  be  carried,  the  diameter  of  the 
boiler  and  the  strength  of  the  material  used.  The  steam 
pressure  has  gradually  been  increased,  so  that  now  it  is  not 


BOILEF3  41 

uncommon  to  find  Scotch  boilers  carrying  from  200  to  250 
pounds  pressure;  the  diameter  has  increased  so  that  boilers 
16  to  18  feet  in  diameter  are  not  rare.  The  time  is  not  far 
distant  when  the  shells  will  have  to  be  so  thick  as  to  make 
this  type  impracticable ;  then  you  will  see  the  watertube  boil- 
ers come  into  greater  use. 

"In  the  early  days  of  steam  machinery,  boiler  building  was 
a  crude  art.  Compared  with  modern  methods  of  construction 
it  was  in  about  the  same  relation  as  early  wooden  shipbuilding 
bears  to  modern  steel  shipbuilding.  If  a  ship  carpenter  made 
anything  that  came  within  a  half  inch  of  the  dimensions  of 
the  stick  of  timber  he  was  shaping,  he  was  supposed  to  be 
quite  accurate.  Old-time  boiler  makers  were  just  about  as 
crude;* they  rarely  had  drawings  to  follow,  a  rough  sketch  on 
a  blackboard  in  the  boiler  shop  sufficing;  holes  were  always 
punched,  and  the  drift-pin  was  used  almost  continuously. 
While  such  methods  were  all  right  for  boilers  using  low  steam 
pressures,  they  would  not  do  nowadays  at  all.  With  the 
high  steam  pressures  now  used,  and  the  large  size  of  the 
boilers,  nothing  but  accurate  design  and  good  workmanship 
will  do.  In  the  early  days  of  boiler  construction  all  rivets 
were  driven  by  hand ;  now  nearly  all  rivets  are  driven  by 
hydraulic  pressure  of  15  to  30  tons,  and  even  with  that  it  is 
almost  impossible  to  keep  some  of  the  seams  and  rivets  from 
leaking. 

"Here  is  a  drawing  (Fig.  i)  of  a  typical  small  Scotch 
boiler  which  will  show  the  general  features  of  this  type. 
It  consists  essentially  of  four  steel  plates  rolled  up  into  the 
form  of  a  cylinder  which  is  known  as  the  shell  of  the  boiler. 
Each  portion  of  the  shell  is  known  as  a  course.  The  courses 
are  lapped  over  one  another  and  riveted  together  by  what 
are  known  as  lap  joints.  The.  longitudinal  seams  come 
together  and  are  joined  by  straps  or  narrow  plates  on  the 
inside  and  outside,  the  whole  when  riveted  together  being 


42  MC  ANDREW  S    FLOATING    SCHOOL 

known  as  a  butt-joint.  In  this  shell  are  two,  three,  or  some- 
times four  smaller  cylindrical  furnaces  which  are  riveted  to 
the  combustion-chamber,  a  semi-cylindrical  box  with  flat  top, 
front  and  back,  in  which  the  combustion  takes  place. 

"You  will  notice  that  these  furnaces  are  not  straight,  but 
consist  of  a  wavy  contour.  In  this  particular  case  they  are 
known  as  suspension  furnaces.  Some  of  them  have  a  series 


FIG.    1. SCOTCH    BOILER.    END   VIEW 

of  corrugations  rolled  into  them,  the  object  of  both  types 
being  to  give  them  sufficient  strength  to  withstand  the  crush- 
ing strain  brought  upon  them  by  the  pressure  of  the  steam. 
It  is  much  easier  for  a  cylindrical  tank  or  figure  to  withstand 
an  internal  or  bursting  pressure  than  it  is  for  it  to  withstand 
an  external  or  collapsing  pressure,  hence  all  furnaces  (in 
Scotch  boilers)  subjected  to  high  pressures  of  steam  on  the 


BOILERS 


43 


outside  must  be  corrugated  in  order  that  they  will  not  col- 
lapse under  the  pressure. 

"From  the  combustion  chamber  to  the  front  head  are  a 
number  of  small  tubes,  usually  from  2  inches  to  4  inches  in 
diameter,  through  which  the  hot  gases  pass  from  the  furnaces 
to  the  uptake  and  thence  to  the  smoke  stack.  It  is  from  these 
tubes  where  the  greater  portion  of  the  steam  is  formed,  as 


FJG-    2. — SCOTCH    ROILER,    LONGITUDINAL   SECTION 


they  are  usually  from  1/16  to  %  inch  in  thickness,  so  that 
the  heat  from  the  gases  is  very  readily  transmitted  to  the 
water  which  surrounds  them. 

"As  the  heads  of  the  boiler  and  the  larger  part  of  the  com- 
bustion chambers  are  flat,  they  must  be  supported  or  braced  at 
intervals  in  order  that  they  may  withstand  the  pressure 
brought  upon  them.  Later  on,  I  will  teach  you  how  to  space 


44  MC  ANDREW'S  FLOATING  SCHOOL 

these  braces  or  stays,  as  they  are  termed,  as  that  is  a  question 
which  will  be  asked  before  you  can  get  your  licenses. 

"In  the  furnaces  of  a  Scotch  boiler  the  grate  bars  are 
arranged  at  about  the  middle  at  the  front  end  and  slope 
slightly  downwards  toward  the  back  end.  The  length  of 
the  grates  is  generally  about  6  feet,  as  that  is  about  as  far  as 
a  good  husky  fireman  can  work  his  fires  properly.  Sometimes 
they  are  $l/2  feet  or  6T/2  feet  long,  but  in  general  you  will  find 
them  averaging  6  feet  in  length.  The  capacity  of  the  fireman 
in  this  respect  really  regulates  the  length  of  most  Scotch 
boilers.  Hence  you  will  find  that  single-ended  boilers  very 
seldom  exceed  n  or  12  feet  in  length,  while  double-ended 
boilers  are  generally  about  20  to  22  feet  in  length — a  double- 
ended  Scotch  boiler  being  practically  two  single-ended  Scotch 
boilers  placed  back  to  back  and  joined  together.  As  I  said 
before,  there  are  a  number  of  other  types  of  shell  boilers,  but 
as  most  of  them  are  obsolete,  we  will  not  waste  any  time  on 
them." 

"What's  obsleet?"  inquired   O'Rourke. 

"  'Obsolete'  means  old-fashioned,  not  up-to-date,"  replied 
the  instructor. 

"I  see,"  replied  O'Rourke;  "it's  something  like  that  hat 
Schmidt  wears  when  he  goes  to  see  his  girl  in  Fishtown." 

"We  will  now  look  into  the  watertube  boiler  question  a 
little.  This  type  of  boiler  is  having  a  hard  time  in  overcom- 
ing the  prejudice  against  it.  At  first  they  were  used  in  swift 
steam  launches  and  torpedo  boats,  on  account  of  the  great 
saving  in  weight  as  compared  with  shell  boilers.  Old-time 
engineers  viewed  them  as  a  sort  of  a  necessary  evil  in  that 
respect  and  pitied  the  men  who  had  to  run  them.  The  battle 
for  supremacy  in  speed  between  the  various  nations  finally 
led  the  more  daring  designers  to  use  them  in  some  swift 
cruisers  and  gunboats.  As  no  great  harm  seemed  to  have 
come  of  this,  the  more  progressive  designers  finally  adopted 


BOILERS  4,- 

this  type  of  boiler  for  battleships.  Old-timers  shook  their 
heads  at  this  move  and  predicted  dire  disaster  for  the  ships 
thus  equipped.  However,  the  results  have  been  so  satisfactory 
that  to-day  every  new  battleship  throughout  the  world  is  fitted 
with  watertube  boilers,  and  they  are  giving  the  greatest  satis- 
faction on  account  of  their  many  superior  qualities. 

"O'Rourke,  you  of  course  know  something  about  watertube 
boilers;  how  many  classes  of  them  do  you  think  there  are?" 
"I  don't  know  much  about  them  myself,"  replied  the  young 
man,  "but  I  heard  a  fellow  out  in  the  shipyard  say  to-day 
that  there  were  two  kinds,  the  macaroni  and  the  spaghetti, 
whatever  they  mean." 

"Ha !  Ha !"  laughed  McAndrew.  "I  suppose  he  meant 
'macaroni'  boilers  were  those  with  large  straight  tubes,  and 
'spaghetti'  as  those  having  small,  bent  tubes.  That  is  rather  a 
good  definition  for  the  two  main  divisions  of  this  class  of 
boilers,  but  so  far  as  different  designs  are  concerned  there 
must  be  two  or  three  hundred,  as  every  designer  has  his  own 
ideas  about  getting  up  a  watertube  boiler.  But  these  various 
kinds  of  boilers  remind  me  of  what  they  say  about  the  fish  in 
the  waters  around  the  Hawaiian  Islands — there  are  298  varie- 
ties, but  they  only  use  three  of  them  to  eat. 

"In  general,  the  main  difference  between  Scotch  and  water- 
tube  boilers  is  that  in  the  former  the  hot  gases  are  inside  the 
tubes  and  the  water  around  the  outside,  while  with  the  latter 
the  water  is  inside  the  tubes  and  the  gases  around  the  out- 
side. 

"Watertube  boilers  usually  consist  of  drums,  headers  and 
tubes,  all  inclosed  in  sheet  metal  casings.  Usually  there  are 
one  or  two  large  drums  on  top  and  two  or  more  smaller  drums 
at  the  bottom,  the  tubes  connecting  the  drums  at  the  top  and 
bottom.  The  feed  water  usually  enters  the  boiler  in  the  top 
drum,  and  is  carried  down  to  the  lower  drums  through  tubes 
or  pipes  known  as  down-flow  tubes.  Sometimes  it  flows  down 


46  MC  ANDREW'S  FLOATING  SCHOOL 

through  the  tubes  themselves.  In  any  event  a  rapid  circula- 
lation  is  started  up  between  the  water  in  the  lower  and  upper 
drums  or  headers.  As  the  water  passes  up  through  the  tubes, 
globules  of  steam  are  formed  which,  discharging  into  the 
upper  drum  with  the  water,  are  separated  by  baffle  plates 
from  the  water  and  pass  out  through  the  dry  pipe  into  the 
main  steam  pipe.  The  tubes  in  which  the  steam  is  formed  are 
known  as  generating  tubes  to  distinguish  them  from  down- 
flow  tubes  when  such  are  fitted  to  the  boiler.  Watertube  boil- 
ers are  usually  rectangular  or  box-shaped,  as  the  casing  sur- 
rounds the  tubes  and  the  furnaces.  In  order  to  prevent  the 
sheet  metal  casing  from  burning,  it  is  usually  lined  with 
asbestos  board  and  fire  brick.  Large  tube  boilers  are  those 
which  have  generating  tubes  3,  4  or  sometimes  5  inches  in 
diameter.  Boilers  built  of  tubes  i  to  2  inches  in  diameter  are 
classed  as  small  tube  or  'spaghetti'  boilers,  as  O'Rourke's 
friend  would  say. 

"Some  engineers  prefer  one  type  and  some  the  other,  but 
if  I  had  anything  to  say  about  fitting  watertube  boilers  to  a 
merchant  vessel,  the  tubes  would  be  as  large  as  practicable 
and  straight  or  nearly  straight,  so  that  they  can  be  cleaned 
and  examined." 

"Why  don't  shipowners  use  watertube  boilers  in  merchant 
vessels?"  inquired  Nelson. 

"That's  hard  to  answer,"  replied  the  Chief,  "but  I  suppose 
it  is  for  the  same  reason  that  many  people  refused  to  ride  on 
the  elevated  road  when  it  was  first  constructed  in  New  York. 
They  had  been  brought  up  to  ride  in  corse  cars  on  the  streets : 
they  knew  they  were  safe  and  sure,  and  although  they  could 
ride  faster  on  the  elevated,  they  preferred  the  safety  which 
they  knew  of,  rather  than  to  take  a  chance  on  the  more  mod- 
ern means  of  transportation  of  which  they  were  afraid.  Such 
a  trait  of  mankind  is  known  as  conservatism,  and  it  is  an 


BOILERS 


47 


excellent  quality  until  it  is  carried  to  excess,  when  it  becomes 
foolishness. 

"The  advantages  watertube  boilers  have  over  Scotch  boilers 
are  many.  The  weight  of  a  watertube  boiler,  with  water,  is 
just  about  one-half  that  of  a  Scotch  boiler  under  the  same 
conditions,  thus  giving  that  much  more  cargo-carrying  ca- 
pacity. Steam  can  be  raised  in  a  half  hour,  as  compared  to 
four  to  six  hours  for  raising  steam  in  a  Scotch  boiler.  There 
is  less  danger  from  a  serious  explosion,  as  the  parts  of  a 
watertube  boiler  liable  to  explode  are  much  smaller  than  the 
great  bulk  of  a  Scotch  boiler,  under  pressure. 

"A  watertube  boiler  need  never  wear  out  entirely,  as  the 
various  parts  can  be  renewed  as  necessity  requires.  When  a 
Scotch  boiler  wears  out,  it  must  be  renewed  in  its  entirety, 
and  generally  at  great  expense  on  account  of  tearing  away  the 
decks  and  joiner  work  above  the  boiler  space. 

"Watertube  boilers  can  be  forced  much  harder,  with  safety, 
than  Scotch  boilers,  as  they  are  in  a  manner  flexible  and  can 
stand  severe  usage  which  ordinarily  starts  a  Scotch  boiler 
leaking. 

"One  of  the  main  features  which  would  appeal  most,  just 
now,  to  you  boys,  is  the  matter  of  cleaning.  In  watertube 
boilers  there  are  no  back  connections  to  sweep — a  task  which 
makes  the  life  of  an  old-time  chimney-sweep  seem  easy  in 
comparison — no  crown  sheets  to  clean  and  sometimes  scale, 
no  cleaning  of  the  inside  of  the  boiler,  where  a  man  must  go 
through  contortions  like  a  ferret  to  get  at  the  heating  sur- 
faces. I  doubt  if  any  more  disagreeable  job  could  have  been 
devised  in  the  days  of  the  Inquisition  than  that  which  befalls 
the  lot  of  a  marine  fireman  when  it  is  boiler  cleaning  time  on 
board  a  ship  fitted  with  Scotch  boilers.  Surely  there  is 
nothing  which  more  discourages  men  from  going  to  sea.  No 
wonder  engineers  hurry  and  get  fat  as  soon  as  possible,  so  that 
it  is  a  physical  impossibility  for  them  to  get  through  a  12  by 


48  MC  ANDREW'S  FLOATING  SCHOOL 

15  inch  manhole.  If  the  stokers  and  coal  passers  could  vote 
on  the  type  of  boiler  to  be  used,  I  am  afraid  the  Scotch  boiler 
would  soon  get  in  the  class  with  Schmidt's  hat. 

"The  disadvantages  claimed  by  opponents  of  watertube 
boilers  are  that  it  takes  more  skill  to  tend  the  feed  on  ac- 
count of  the  smaller  quantity  of  water  in  the  watertube  type. 
This,  I  am  told,  is  more  imaginary  than  real,  although  it 
must  be  admitted  that  a  water  tender  must  be  onto  his  job 
at  all  times  and  keep  his  eyes  on  the  glass.  So,  too,  should 
a  water  tender  with  any  other  type  of  boiler,  as  that  is  a 
duty  where  day  dreaming  does  not  go.  It  is  also  claimed  that 
strictly  fresh  water  must  be  fed  into  watertube  boilers  at 
all  times,  but,  as  a  matter  of  fact,  that  is  so  with  a  modern 
Scotch  boiler  if  its  efficiency  is  to  be  maintained.  The  care 
of  marine  boilers  of  any  type  is  one  of  the  most  important 
duties  on  board  ship.  Carelessness  on  the  part  of  anyone 
connected  with  the  handling  of  boilers  is  not  only  dangerous 
to  all  on  board,  but  frequently  results  in  large  repair  bills 
and  operating  expenses.  The  most  successful  engineers  are 
those  who  keep  the  boilers  in  good  condition  and  operate  them 
intelligently.'* 


CHAPTER    VII 

Boiler  Fittings 

"How  many  fittings  are  there  on  a  marine  boiler?"  inquired 
McAndrew. 

"Four,  sir,"  said  Nelson. 

"Only  four,  eh?     Well,  what  are  they?" 

"The  steam  gage,  gage  glass,  shovel  and  slice  bar,"  replied 
Nelson. 

"Oh !  come  off,"  said  O'Rourke,  "the  shovel  and  slice  bar 
are  what  the  highbrows  call  the  'implements  of  your  trade' — 
they're  not  fittings." 

"Well,  O'Rourke,"  said  the  teacher,  "how  many  do  you 
think  there  are?" 

"Oh!  at  least  half  a  dozen,"  replied  he,  "but  for  the  life 
of  me  I  can't  think  of  their  names  just  now." 

"O'Rourke,  you  remind  me  of  the  fellow  who,  when  falling 
off  the  water  wagon,  paused  in  the  act  of  taking  a  drink  and 
said,  There  are  a  dozen  good  reasons  why  I  shouldn't  drink 
this  whiskey,  but  for  the  life  of  me  I  can't  think  of  one  of 
them  now' — and  then  he  took  the  drink.  I  don't  think  you 
have  tried  very  hard  to  think  of  the  necessary  fittings  on  a 
boiler,  but,  at  any  rate,  I'll  remind  you  of  some  of  them. 

"You  all  know  of  the  safety  valves,  which  are  generally 
made  in  pairs  and  are  bolted  to  the  highest  part  of  the  boiler. 
The  old-fashioned  safety  valves  were  of  the  ball-and-lever 
type,  but  they  are  not  used  to  any  great  extent  these  days,  as 
they  are  poorly  adapted  for  high  pressures,  or  in  fact  for  use 
on  shipboard  at  all.  One  of  the  most  important  duties  about 


5O  MC  ANDREW'S    FLOATING    SCHOOL 

the  fireroom  is  to  see  that  the  so-called  easing  gear  for  lifting 
the  safety  valves  off  their  seats  is  kept  well  oiled  and  in  good 
working  condition.  At  least  every  other  day  the  valve  should 
be  lifted  off  its  seat  for  an  instant  to  see  if  the  springs  are 
working  well.  It  might  be  necessary  to  open  the  safety 
valves  in  a  hurry  some  day,  and  if  the  gear  is  not  kept  in 
good  condition  they  would  fail  at  the  critical  moment. 

"The  stop  valves  on  boilers  are  very  important  fittings,  as 
they  control  the  passage  of  the  steam  to  the  engines.  On 
every  boiler  you  will  find  a  large  valve  known  as  the  main 
stop  valve,  and  a  smaller  one,  the  auxiliary  stop  valve.  These 
valves,  too,  should  have  their  stems  lubricated  and  kept  in 
such  condition  that  they  can  be  worked  easily.  In  this  con- 
nection I  want  to  warn  you  young  men  against  opening  a  stop 
valve  on  a  boiler  suddenly — many  a  good  man  has  gone  to 
Kingdom  Come  by  not  bearing  that  in  mind.  You  must  re- 
member that  a  sudden  release  of  steam  often  causes  large 
gulps  of  water  to  be  carried  with  the  steam  through  the  valve 
and  into  the  steam  pipe,  where  a  water  hammer  is  instantly 
formed  and  often  with  the  result  of  bursting  the  pipe.  Even 
if  no  water  is  carried  out  with  the  steam,  the  pipes  are  cold, 
and  the  sudden  condensation  results  also  in  a  water  hammer. 
When  you  open  a  stop  valve,  just  'crack'  it  at  the  start — by 
that  I  mean  to  turn  the  handwheel  a  mere  trifle  until  you  can 
hear  the  steam  hissing  through  the  slight  opening.  Then 
wait  until  you  can  count  at  least  200  before  you  give  it  another 
slight  turn." 

"It's  too  hot  up  there  to  be  counting  very  much,"  inter- 
jected O'Rourke. 

"Yes,  but  it  isn't  nearly  so  hot  up  there  as  the  place  you 
might  go  to  if  you  opened  the  valve  suddenly,"  said  Mc- 
Andrew. 

"We  have  seen  how  to  get  the  steam  out  of  a  boiler,  but 
after  all  it  is  of  even  greater  importance  to  get  the  water  into 


BOILER  FITTINGS  ej; 

it,  for  if  you  fail  to  keep  the  water  flowing  into  a  boiler  under 
steam,  there  would  soon  be  something  doing. 

"Schmidt,  do  you  know  what  a  check  valve  is?" 

"No,  sir,"  replied  he,  "I  don't  know  just  what  it  is,  but  I 
know  where  it  is,  and  I  know  that  you  open  it  to  let  the  water 
in  the  boiler  after  you  start  the  feed  pump." 

"That's  something  to  know,"  continued  McAndrew,  "but 
like  a  certain  brand  of  breakfast  food,  'there's  a  reason  for 
it.'  A  check  valve  is  one  which  allows  water  to  pass  in  only 
one  direction— that  is,  from  the  pump  to  the  boiler.  It  is 
made  that  way  so  that  in  case  the  feed  pipe  should  burst,  the 
scalding  hot  water  and  steam  from  the  boiler  would  not  rush 
out  through  the  opening  in  the  feed  pipe." 

"I'm  on,"  said  O'Rourke,  "it's  like  a  one-way  ticket  to 
Coney  Island— you  can  get  down  there  all  right,  but  you  can't 
get  back  if  you  blow  in  all  your  money." 

"Recently  all  marine  boilers  were  required  to  have  two 
separate  openings  in  the  shell  and  two  separate  check  valves, 
a*  main  and  an  auxiliary,  to  regulate  the  admission  of  the 
feed  water,  so  that  if  one  gives  out  the  other  can  be  used. 
There  is  also  a  stop  valve  located  between  the  check  valve  and 
the  boiler  shell,  so  that  in  case  of  accident  to  the  check  valve 
the  stop  valve  can  be  closed  and  repairs  made  to  the  check. 
It  pays  to  take  every  possible  precaution  in  regard  to  such  an 
important  matter. 

"After  we  have  provided  means  for  getting  ihe  water  in 
and  the  steam  out  of  a  boiler,  the  next  thing  in  importance 
is  to  have  some  way  to  ascertain  the  level  or  height  of  the 
water  in  the  boiler.  Here,  too,  every  precaution  must  be 
taken,  for  it  is  a  very  serious  matter.  You  all  have  seen  the 
gage  glasses  and  how  careful  the  water  tenders  are  to  watch 
the  level  of  the  water  in  them.  The  gage  glass  is,  therefore, 
the  most  important  of  the  means  employed  for  determining 
the  water  level.  As  a  further  precaution,  there  are  four  gage 


52  MC  ANDREW  S   FLOATING    SCHOOL 

cocks  usually  fitted  on  the  side  or  in  the  front  of  the  boilers 
at  about  the  desired  water  level.  I  must  confess  that  it  i: 
very  difficult  for  anyone,  except  a  locomotive  engineer,  tc 
tell  exactly  the  water  level  by  means  of  these  cocks.  It  takes 
a  trained  eye  and  a  trained  ear  to  distinguish  between  the 
steam  and  water  when  a  ship  is  rolling.  The  locomotive  engi- 
neer has  to  depend  on  gage  cocks  almost  entirely,  as  it  is 
impracticable  to  fit  gage  glasses  on  a  locomotive.  On  board 
ship  the  men  rely  almost  entirely  on  the  gage  glass,  so  they 
do  not  get  much  practice  with  the  try  cocks.  I  would  rather 
take  my  chances  by  having  two  gage  glasses  fitted,  as  it  is 
almost  certain  that  both  glasses  will  never  be  broken  or  out 
of  order  at  the  same  time. 

"I  suppose  you  have  noticed  that  toy  safety  valve  just  over 
the  uptakes  on  our  boilers.  If  you  didn't  see  the  main  safety 
valves,  you  'might  get  the  idea  that  the  boiler  designer  had 
put  a  boy  to  do  a  man's  work.  The  object  of  this  little  valve, 
which  should  always  be  a  lever  valve  with  a  sliding  weight, 
is  to  give  warning  that  the  steam  is  almost  up  to  the  blowing- 
off  point;  hence  it  is  known  as  a  sentinel  valve.  If  for  any 
reason  the  springs  in  the  safety  valve  refuse  to  work,  this 
little  valve  is  sometimes  very  useful. 

"You,  of  course,  have  heard  of  the  blow  valves  on  the 
boilers.  These  are  usually  fitted  to  all  boilers ;  one  is  known 
as  the  'surface  blow'  and  the  other  as  the  'bottom  blow.'  In 
boiling  water  the  lighter  impurities,  such  as  grease  and  other 
substances,  which  float  on  water,  are  driven  to  the  surface  of 
the  water.  O'Rourke,  I  know,  has  often  watched  his  mother 
skirri  the  grease  off  the  top  of  the  boiling  pot  of  soup,  when 
he  was  a  boy  and  was  so  hungry  he  could  hardly  wait  for 
dinner  time.  The  idea  of  the  surface  blow  on  a  steam  boiler 
is  about  the  same,  only  in  a  boiler  there  is  a  pipe  connecting 
the  blow  valve  to  what  is  known  as  a  'scum  pan,'  usually 
located  in  about  the  center  of  the  boiler  and  at  about  the  low- 


BOILER    FITTINGS 


53 


water  level.  At  intervals  it  is  advisable  to  open  the  surface 
blow  valve  and  give  it  a  slight  blow  in  order  to  remove  the 
grease  and  other  floating  impurities  from  the  boiler  water. 

"The  bottom  blow  valve  is  located  at  the  lowest  part  of  the 
boiler,  and  there  is  usually  a  perforated  iron  pipe  connected 
to  the  blow  valve.  Mud  and  heavy  impurities  collect  at  the 


FIG.    3. BOURDON    STEAM    GAGE 

bottom  of  the  boiler,  and  an  occasional  blow  will  remove  such 
substances.  This  bottom  blow  is  sometimes  used  to  pump  out 
the  boiler  when  it  is  desired  that  it  be  emptied. 

"One  of  the  most  important  of  the  so-called  'boiler  fittings' 
is  the  steam  gage,  for  it  is  by  means  of  this  instrument  that 
we  are  enabled  to  determine  the  actual  pressure  of  the  steam 
in  the  boiler. 

"Fig.  3  is  a  picture  of  the  type  of  steam  gage  usually  fitted 
to  marine  boilers.  By  means  of  a  circular  tube  having  an  ellip- 
tical section  as  shown,  when  the  pressure  is  applied  to  the 


54  MC  ANDREW  S  FLOATING  SCHOOL 

inside  of  the  tube  it  tends  to  assume  a  round  section,  and  the 
tube  itself  tends  to  straighten  out  owing  to  the  greater  area 
subjected  to  pressure  on  the  outside  surface.  The  free  end 
of  the  tube  is  connected  by  gear  wheels  and  pinions  to  the 
needle  on  the  face  of  the  dial  which,  when  properly  adjusted, 
records  the  steam  pressure.  Remember,  as  I  have  called  to 
your  attention  before,  boiler  gages  only  record  the  pressure 
above  the  atmosphere  and  not  the  absolute  pressure. 

"Steam  gages  on  boilers  should  be  tested  at  intervals  to  see 
that  they  are  adjusted  correctly,  as  it  frequently  happens  that 
gages  on  different  boilers,  all  connected  up,  show  a  variance 
of  from  i  to  10  pounds.  I  once  had  a  green  fireman  with  me 
who  nearly  broke  his  back  trying  to  get  the  steam  on  his 
boiler  up  to  the  same  pressure  carried  by  the  other  boiler ; 
as  a  matter  of  fact,  the  gage  on  his  boiler  recorded  5  pounds 
less  pressure,  due  to  its  being  out  of  adjustment.  The  older 
firemen  let  him  hustle  for  a  day  or  so  before  they  told  him 
the  gage  was  wrong." 

"Why  do  they  always  put  that  crook  in  the  pipe  to  the  steam 
gage?"  inquired  Nelson. 

"That's  because  most  water  tenders  are  so  used  to  seeing 
snakes  that  they  want  things  to  look  natural  to  them  when 
they  watch  the  steam  gage,"  volunteered  O'Rourke. 

"O'Rourke  is  as  nearly  right  as  usual,"  replied  McAndrew. 
"The  real  reason  is  that  if  the  steam  acted  on  the  Bourdon 
tube  direct,  the  expansion  due  to  the  varying  temperatures 
would  make  it  record  inaccurately.  Hence,  the  crook  serves 
the  purpose  of  a  trap,  as  it  fills  with  water  by  the  condensa- 
tion of  the  steam,  and  this  water  is  forced  into  the  tube  by 
the  steam. 

"Another  important  fitting  is  the  air  cock,  which  is  usually 
placed  at  the  highest  part  of  the  boiler.  When  fires  are  started 
this  cock  should  be  opened  in  order  that,  as  the  steam  is  raised, 


BOILER    FITTINGS 


55 


all  the  air  in  the  boiler  will  be  driven  out.     It  should  not  be 
closed  until  live  steam  issues  from  the  cock. 

"To  impress  upon  you  the  importance  of  paying  attention  to 
even  the  smallest  details  around  boilers  under  steam,  I  want 
to  call  your  attention  to  a  boiler  explosion  on  board  an 
American  vessel  not  many  years  ago,  when  over  thirty  lives 
were  lost  and  great  damage  was  done  because  a  fireman  who 


FIG.    4. HYDROKINETER 

was  sent  on  top  of  the  boilers  to  close  the  air  cock  not  only 
closed  that  fitting  but  also  shut  off  the  cock  in  the  small  steam 
pipe  which  led  to  the  steam  gage.  The  result  was  that  al- 
though no  steam  showed  on  the  gage  the  pressure  in  the 
boiler  rose  to  the  bursting  point  and  the  explosion  followed. 
Always  remember  that  if  you  make  a  mistake  like  that  you 
endanger  not  only  your  own  life  but  the  lives  of  everybody 
else  on  the  ship. 

"Some  boilers  are  fitted  with  what  is  known  as  a  'hydro- 
kineter/  which  means  literally  a  water  heater. 

"One  of  the  great  faults  of  all  Scotch  boilers  is  that  the 
water  under  the  furnaces  and  combustion  chambers  does  not 
circulate  properly,  or,  in  other  words,  it  is  dead.  The  hydro- 


56  MC  ANDREW'S  FLOATING  SCHOOL 

kineter  is  usually  located  in  this  dead  water,  and  when  live 
steam  is  admitted  it  acts  on  the  principle  of  an  ejector  and 
causes  the  water  to  circulate  as  indicated  by  the  arrows  in  the 
sketch.  I  have  seen  boilers  carrying  over  100  pounds  of 
steam  when  you  could  bear  your  hand  on  the  bottom  of  the 
shell  because  of  the  presence  of  the  dead  water  underneath 
the  furnaces.  Some  engineers  when  raising  steam  will  con- 
nect the  auxiliary  feed  pump  so  as  to  draw  this  cold  water 
out  through  the  bottom-blow  connection  and  discharge  it 
through  the  auxiliary  feed  check  valve,  thus  causing  an  arti- 
ficial circulation.  There  are  also  several  very  good  patented 
devices  for  bringing  about  this  much  desired  circulation. 

"Another  item  which  might  be  classed  as  a  boiler  fitting  is 
the  so-called  fusible  plug  which  the  law  requires  shall  be  fitted 
to  the  tops  of  combustion  chambers  and  at  other  important 
parts  of  the  boiler.  This  consists  of  a  brass  plug  screwed 
into  a  tapped  hole ;  the  center  of  this  plug  is  filled  with  a  soft 
metal,  such  a  Banca  tin,  which,  when  not  covered  by  water, 
will  melt  and  allow  the  steam  to  blow  through  the  opening, 
thus  acting  as  a  safety  vent." 


CHAPTER  VIII 
Forced  Draft 

"Before  leaving  the  subject  of  boilers,  we  will  look  into  the 
matter  of  forced  draft.  Although  this  ship  is  not  fitted  with 
any  system  for  that  purpose,  many  other  ships  are,  so  it  will 
be  well  for  you  to  know  about  the  various  methods  adopted. 

"I  have  told  you  that  air  is  just  as  important  for  combus- 
tion as  coal  itself.  When  fires  are  started  in  the  furnaces  the 
smoke  and  hot  gases  go  up  through  the  tubes  and  uptakes  to 
the  funnel  or  stack.  You  might  wonder  why  they  don't  come 
back  through  the  furnace  and  ash  pit  doors.  The  reason  why 
they  do  not  is  due  to  what  is  known  as  draft,  or  the  tendency 
to  go  up  instead  of  down.  Air  when  heated  becomes  less 
dense  or  lighter  in  weight,  hence  it  is  that  at  the  furnace  front 
and  under  the  grate  bars  there  is  a  tendency  of  the  air  to  flow 
through  and  up.  This  tendency  is  due  to  the  difference  in 
weight  of  a  column  of  cold  air  of  the  height  equal  to  the  dis- 
tance between  the  level  of  the  grates  and  the  top  of  the  stack, 
and  the  weight  of  a  similar  column  of  heated  air  of  the  same 
height.  This  difference  in  pressure  or  weight  is  usually  very 
slight,  but  sufficient  to  cause  enough  air  to  flow  into  the  fur- 
naces to  keep  up  a  reasonable  rate  of  combustion.  In  gen- 
eral, the  higher  the  funnel  the  greater  the  difference  in  pres- 
sure, and  consequently  the  better  the  draft. 

"Draft  is  usually  measured  by  a  device  such  as  is  shown 
in  Fig.  5.  One  end  of  the  U-shaped  tube,  which  is  located  in 
the  fire-room,  is  open  to  the  air  pressure  in  the  fire-room,  the 
other  is  connected  by  a  rubber  tube  to  the  space  under  the 
grates.  The  difference  between  the  two  pressures  compels  the 


MC  ANDREW  S  FLOATING  SCHOOL 


water  to  lower  in  the  free  end  and  rise  in  the  end  connected  to 
the  tube.  We  thus  speak  of  draft  as  measured,  not  in  pounds, 
but  in  inches  or  fractions  of  an  inch  of  water.  Were  the  pres- 
sure to  be  expressed  in  actual  weight,  such  as  a  steam  gage 
shows,  you  would  find  that  i  inch  of  water  pressure  would 
equal  only  two-thirds  of  an  ounce. 

"Ordinarily  natural  draft  on  a  steamer  of  this  size  is  about 
Y^.  to  y§  inch  of  water,  and  such  a  pressure  under  ordinary 


FIG.    5. DRAFT   GAGE 

conditions  is  sufficient  to  burn  enough  coal  to  produce  the 
desired  speed  of  a  vessel.  There  are  times,  however,  when 
greater  speed  is  demanded  than  can  be  produced  by  natural 
draft  pressures.  Fast  passenger  vessels,  steam  yachts  and 
torpedo  boats  must  go  at  full  speed  either  all  of  the  time  or 
at  intervals,  and  under  these  conditions  a  greater  rate  of  com- 
bustion must  be  obtained.  Hence  it  becomes  necessary  to  use 
what  is  termed  'forced'  draft,  or  in  other  words  apparatus 
for  furnishing  a  greater  quantity  of  air  to  the  furnace  than 


FORCED   DRAFT  29 

would  naturally  flow  in  due  to  the  difference  in  weight  of 
the  two  columns  of  air. 

"The  most  primitive  system  of  forced  draft  is  probably 
illustrated  by  the  boy  who,  while  shooting  firecrackers,  blows 
on  a  piece  of  punk  in  order  to  make  the  cracker  fuses  light 
easier." 

"Chief,"  interrupted  Schmidt,  "I  think  we  could  have  a  good 
forced  draft  system  on  board  this  ship  by  making  O'Rourke 
get  on  his  hands  and  knees  and  blow  under  the  grate  bars;  he's 
about  as  good  a  blower  as  I  know  of." 

"That's  all  right,"  retorted  O'Rourke,  "about  my  forced 
draft ;  I  know  some  one  not  very  far  off  who  couldn't  be  used 
for  that  purpose — he  eats  too  much  Limburger — his  breath 
would  put  out  almost  any  fire  instead  of  making  it  burn 
faster." 

"If  you  young  men  are  running  a  debating  club,  we  had 
better  quit  right  here  and  let  you  fight  it  out,"  said  McAndrew. 

"Please  go  on  with  the  forced  draft,  Chief,"  pleaded  Pierce, 
who  was  by  far  the  most  earnest  of  the  Floating  School  under- 
graduates. 

"To  return  to  the  subject,"  continued  the  instructor,  "forced 
draft  on  board  steam  vessels  is  produced  by  one  of  four  gen- 
eral systems. 

"The  first  and  most  generally  used  is  the  closed  fire-room 
type,  where  all  parts  of  the  fire-room  and  boiler  compartment 
are  made  as  nearly  air-tight  as  practicable,  and  the  air  is 
forced  into  the  space  by  means  of  centrifugal  blowers,  which 
draw  in  the  air  from  ventilators  or  sometimes  from  the  engine 
room  and  discharge  directly  into  the  fire-room.  As  there  is  no 
other  escape  except  through  the  grate  bar  spaces,  the  fires  are 
forced  by  means  of  the  greatly  increased  amount  of  oxygen 
available  for  the  purposes  of  combustion.  This  system  is 
more  comfortable  for  the  firemen,  as  the  cooler  air  from  out- 
side makes  the  temperature  lower.  It  gives,  however,  a  some- 


6o  MC  ANDREW'S  FLOATING  SCHOOL 

what  uncomfortable  feeling  in  your  ears,  as  the  pressure  is,  of 
course,  greater  than  the  ordinary  pressure  of  the  atmosphere." 

"Why  can't  you  put  cotton  in  your  ears?"  inquired  Nelson. 

"You  could  if  you  wanted  to,  but  the  pressure  would  be  on 
the  cotton  just  the  same,  and  there  would  still  be  a  feeling  of 
pressure  on  your  ear  drums. 

"A  steam  jet  in  the  funnel  is  another  system  of  forced  draft, 
and  probably  the  simplest  that  can  be  devised.  The  most 
efficient  jet  seems  to  be  one  that  is  located  right  in  the  center 
of  the  stack,  and  so  proportioned  as  to  blow  the  steam  out 
through  a  conical  opening,  causing  it  to  spread  out  to  the  sides 
of  the  stack  and  creating  a  lowering  of  the  pressure  in  the 
up-take,  which  causes  a  more  rapid  flow  of  the  air  through  the 
fires.  Steam  jets  are  not  very  economical  for  marine  purposes, 
as  they  waste  too  much  valuable  fresh  water. 

"On  harbor  boats  or  on  vessels  running  in  fresh  water,  they 
provide  a  simple  and  inexpensive  forced  draft.  All  steam 
locomotives  use  what  practically  amounts  to  steam  jet  forced 
draft,  as  you  probably  know  that  the  exhaust  steam  from  the 
two  cylinders  is  turned  into  the  stack,  which  with  the  engine 
at  full  speed  produces  a  very  strong  draft. 

"Ash  pit  draft  is  another  of  the  four  systems  used.  In  this 
the  air  is  led  from  blowers  through  sheet  iron  ducts,  directly 
to  the  ash  pits,  where  it  is  discharged  underneath  the  grate 
bars.  When  it  becomes  necessary  to  charge  the  furnace  with 
coal  the  draft  must  be  shut  off,  else  the  flames  and  gases  will 
be  forced  out  of  the  furnace  doors  into  the  faces  of  the  fire- 
men. The  best  type  of  ash  pit  forced  draft  is  where  the  air 
from  the  blowers  is  passed  through  a  heater  arranged  in  the 
up-takes,  whereby  some  of  the  heat  which  would  otherwise  be 
lost  in  the  escaping  gases  is  utilized  in  warming  the  air  which 
is  used  for  combustion. 

"Induced  draft  is  used  on  many  vessels;  this  is  caused  by 
locating  a  large  blower  at  the  base  of  the  stack,  which  draws 


FORCED    DRAFT  6l 

the  gases  from  the  up-takes  and  discharges  them  higher  up 
in  the  stack  or  funnel.  This  is  much  less  expensive  than  the 
closed  fire-room  system,  and  in  case  of  any  leaks  in  the 
breeching  or  up-takes  the  air  from  the  outside  rushes  in, 
and  thus  prevents  the  escape  of  gases  into  the  fire-room  space, 
as  frequently  occurs  when  natural  or  forced  draft  of  the  other 
types  is  used, 

'This  will  close  my  remarks  on  the  subject  of  boilers,  and 
as  O'Rourke  has  fallen  asleep  twice  in  the  last  ten  minutes.  I 
think  you  had  all  better  'turn  in/" 


CHAPTER  IX 

Engines 

On  the  following  evening  McAndrew  began  his  lecture  by 
saying : 

"Young  men,  we  are  now  about  to  take  up  a  subject  which 
I  know  will  interest  you  greatly,  as  you  all  hope  to  be  engi- 
neers ;  that  is,  men  capable  of  running  and  caring  for  engines. 

"O'Rourke,  what,  in  your  opinion,  is  an  engine?" 

"Let  me  see,"  replied  the  spokesman  of  the  class.  "An 
engine  is  something  that  makes  the  wheels  go  around." 

"You're  right,"  replied  McAndrew ;  "shorn  of  all  qualifying 
verbiage  that  is  really  what  it  does,  and  that  is  its  principal 
function.  But  how  does  it  do  it?  that's  the  question.  You 
all  know  that  when  everything  is  in  readiness  the  man  on 
watch  opens  the  throttle  and  the  screw  begins  to  revolve.  If 
that  was  the  extent  of  your  knowledge  you  would  be  simply 
engine  starters  and  stoppers,  but  I  trust  you  will  know  more 
about  it  before  you  get  your  licenses. 

"As  I  told  you  before,  if  a  cubic  inch  of  water  is  turned  into 
steam  the  latter  would,  under  atmospheric  pressure,  expand 
into  almost  a  cubic  foot  of  steam.  When,  however,  it  is  con- 
fined in  a  steam-tight  vessel  such  as  a  boiler,  it  cannot  expand 
into  such  a  large  volume,  and  consequently  the  pressure  rises. 
When  it  reaches,  say,  a  pressure  of  180  pounds  per  square 
inch,  it  has  a  tendency  to  expand  into  the  volume  which  it 
would  occupy  if  all  pressure  were  removed.  It  is  this  tendency 
to  expand  which  makes  steam  valuable  as  a  source  of  power, 
and  the  greater  the  pressure  the  greater  the  expansion.  In 


ENGINES  63 

this  connection  you  should  remember  the  fundamental  rule 
that  the  pressure  multiplied  by  the  volume  is  always  equal. 
Thus  if  we  have  one  cubic  foot  of  steam  at  a  pressure  of  100 
pounds  per  square  inch,  it  has  the  same  expansive  effect  as 
would  10  cubic  feet  of  steam  at  a  pressure  of  10  pounds  per 
square  inch. 

"When  steam  is  released  from  the  boiler  and  enters  an  en- 
gine, it  tends  to  expand  like  a  compressed  spring  if  the  weight 
is  taken  from  it.  When  it  reaches  the  cylinder  of  an  engine 
through  the  pipe  connecting  the  boiler  to  the  cylinder  it  starts 
to  expand,  and  as  the  sides  of  the  cylinder  and  the  cylinder 
head  are  fixed  and  rigid,  the  only  way  it  can  increase  in  vol- 
ume is  to  force  the  movable  piston  in  the  cylinder  up  or  down 
as  the  case  may  be.  This  up  and  down  motion  of  the  piston 
is  transmitted  through  the  piston  and  connecting  rods  of  the 
engine  to  the  crankshaft  which  rotates  and  turns  the  propeller. 

"There  have  been  numerous  kinds  of  engines  invented  to 
utilize  the  expansive  force  of  steam,  and  step  by  step  they  have 
been  improved  upon,  until  now  practically  nine-tenths  of  all 
the  marine  engines  in  use  are  of  the  vertical,  inverted,  triple 
and  quadruple  expansion  types  and  the  more  recent  type 
known  as  the  turbine.  Obsolete  types,  or  those  which  have 
outlived  their  usefulness,  are  of  interest  to  show  what  steps 
have  had  to  be  taken  to  reach  the  present  standards,  but  for 
your  purposes  the  modern  engines  are  those  to  which  you 
should  devote  most  of  your  attention. 

"Nelson,  what  is  your  definition  of  a  triple-expansion 
engine  ?" 

"One  that  has  three  cylinders,  sir,"  he  promptly  replied. 

"That  is  true  in  part,"  said  McAndrew,  "as  the  majority 
of  triple-expansion  engines  do  have  three  cylinders;  but  I 
want  to  disabuse  your  mind  of  the  idea,  which  so  many  young- 
sters seem  to  have,  that  the  number  of  cylinders  determines 
the  type  of  the  engine.  Some  compound  engines  have  three 


64  MC  ANpREW's  FLOATING  SCHOOL 

cylinders,  some  triple-expansion  engines  have  four  and  even 
five  cylinders,  so  you  see  that  your  definition  does  not  hold  in 
all  cases. 

"Engines  derive  their  classification  or  type  from  what  we 
may  call  the  different  stages  in  which  the  expansive  effect  of 
the  steam  is  utilized.  A  simple  engine  is  one  in  which  all  of 
the  expansive  effect  is  utilized  in  one  stage ;  a  compound 
engine  is  one  in  which  this  is  accomplished  in  two  stages  or 
periods ;  a  triple  expansion  type  is  one  in  which  it  takes  three 
stages  of  expansion  to  get  all  the  work  from  the  steam.  Thus 
if  we  are  using  steam  at  180  pounds  gage  pressure  in  the  high- 
pressure  cylinder  (or  first  expansive  stage)  it  partly  expands 
during  the  first  step  to  a  pressure  of,  say,  60  pounds,  when  it 
is  exhausted  into  the  second  stage,  or  the  intermediate  cylin- 
der, as  it  is  termed;  there  the  expansive  force  is  reduced  to, 
say,  10  pounds  gage  pressure,  when  it  again  passes  to  another 
stage,  or  the  low-pressure  cylinder,  in  which  it  is  expanded 
down  to  an  absolute  pressure  of  perhaps  2  pounds,  depending 
upon  the  vacuum  carried  in  the  condenser.  The  whole  process 
might  be  compared  to  wringing  the  water  out  of  a  tablecloth. 

"Now,  O'Rourke,  I  suppose  when  you  were  a  boy  you  have 
helped  your  mother  with  the  family  wash  on  Mondays,  haven't 
you  ?" 

"Sure  thing,"  he  replied,  "whenever  I  couldn't  stick  my  kid 
brother  on  the  job." 

"Well,  you  might  remember  that  your  mother  would  take  a 
tablecloth  out  of  the  bluing  water  and  give  it  a  twist,  thus 
rinsing  out  considerable  water ;  after  a  while  she  picked  it 
up,  took  hold  of  one  end  of  it  while  you  took  the  other  end, 
and  you  both  twisted  it  as  hard  as  you  could,  with  the  result 
that  more  water  came  out  of  it.  Finally,  she  put  it  in  the 
wringer,  for  which  you  probably  furnished  the  motive  power, 
and  still  more  water  ran  out  of  it.  Well,  that's  the  idea  of  a 
triple-expansion  engine;  it  takes  three  processes  to  get  the 


ENGINES  65 

work  out  of  the  steam,  just  as  it  took  three  processes  for  you 
to  get  the  water  out  of  that  tablecloth." 

"Gee !"  said  O'Rourke,  "I  must  have  been  a  triple-expansion 
laundryman  and  didn't  know  it !" 

"I  think  from  the  sound  of  the  hot  air  which  escapes  from 
him  he  must  have  been  a  simple  one,"  volunteered  his  rival, 
Schmidt. 

"Having,  I  hope,  fixed  in  your  mind  the  idea  of  a  triple- 
expansion  engine,  we  will  now  investigate  some  of  its  parts. 
The  cylinders,  naturally,  are  the  most  important  of  these,  as 
in  the-m  the  work  of  the  steam  is  performed. 

"I  suppose  you  know  that  the  name  comes  from  the  geomet- 
rical figure  known  as  a  cylinder,  as  the  inside  or  working 
surface  of  the  so-called  cylinders  is  perfectly  cylindrical;  that 
is,  it  is  exactly  circular  in  section  at  any  point.  The  outside 
of  a  marine  engine  cylinder  is  anything  but  cylindrical,  owing 
to  the  valve  chests,  flanges,  etc.,  necessary  to  fit  it  for  its  work. 

"All  steam  engine  cylinders  are  made  of  cast  iron,  because 
that  is  the  ideal  material  for  the  purpose;  no  other  material 
would  fulfill  all  the  requirements. 

"The  thickness  of  cylinders  depends  upon  several  things, 
the  most  important  of  which  is  the  strain  which  it  is  required 
to  withstand.  However,  you  will  find  that  they  are  always 
made  much  heavier  than  actually  necessary,  as  all  parts  of 
machinery  are,  when  designed,  given  what  is  termed  a  'factor 
of  safety.'  That  is,  after  you  have  calculated  how  thick  any 
part  should  be  from  a  theoretical  standpoint,  you  make  it  act- 
ually three,  four  or  even  five  times  as  thick,  then  you  will  be 
deadsure  that  you  are  on  the  safe  side.  You  might  think  from 
that  statement  that  designing  engineers  do  not  have  much 
nerve,  and  as  a  matter  of  fact  many  of  them  are  lacking  in  that 
essential.  Experience  has,  however,  taught  them  to  be  on  the 
safe  side,  for  in  marine  machinery  particularly  emergencies 
develop  in  the  most  unusual  way  at  times  which  upset  all 


66  MC  ANDREW'S  FLOATING  SCHOOL 

theories.  After  cylinders  have  been  in  use  for  a  number  of 
years  they  may  become  badly  scored  or  out  of  round,  in  either 
of  which  cases  it  is  necessary  to  have  them  rebored.  Conse- 
quently the  designer  must  keep  that  contingency  in  mind  when 
determining  the  thickness.  You  can  always  cut  off  portions  of 
a  casting,  but  you  can  rarely  add  anything  to  them,  hence 
they  should  be  heavy  enough  at  the  start. 

"Attached  to  and  cast  with  the  cylinders  are  the  valve  chests 
which  contain  the  valves  for  regulating  the  entrance  and  exit 
of  the  steam  to  and  from  the  cylinders.  They,  vary  in  size  and 
shape  in  accordance  with  the  type  and  sizes  of  valves  used. 

"The  cylinder  heads  are,  of  course,  a  necessary  adjunct  to 
close  up  the  tops  of  the  cylinders.  Relief  valves  are  always 
fitted  at  the  top  and  bottom  of  each  cylinder  to  relieve  any 
steam  pressure  in  excess  of  the  safe  working  pressure,  but 
principally  to  relieve  the  cylinders  of  water  pressure,  in  case,  as 
may  happen,  water  collects  in  the  cylinders,  either  from  being 
carried  over  from  the  boilers  with  the  steam  or  from  being 
condensed  in  the  cylinders  before  they  are  properly  warmed 
up.  Water  is,  as  you  may  have  observed,  practically  non- 
compressible,  so  that  if  any  collects  either  at  the  top  or  bottom 
of  the  cylinder,  and  the  piston  moves  rapidly  against  it,  some- 
thing must  give  way.  The  relief  valves,  if  properly  adjusted, 
serve  the  purpose  of  allowing  the  water  to  escape  and  of  pre- 
venting an  accident  to  the  head  or  to  the  cylinder  itself. 

"To  prevent  too  great  a  radiation  of  heat  from  the  cylinders 
they  are  lagged  with  blocks  of  a  non-conductor,  such  as  mag- 
nesia or  asbestos,  i]/2  to  2  inches  thick,  held  in  place  either  by 
wood  staving  or  planished  sheet  iron.  This  accomplishes  two 
purposes :  one  of  making  the  engine  more  efficient  by  prevent- 
ing the  loss  of  heat,  and  the  other  of  keeping  the  engine  room 
from  becoming  too  hot  for  comfort. 

"O'Rourke,  do  you  know  what  a  non-conductor  is  ?" 

"It  must  be  a  conductor  that  don't  belong  to  the  union," 
replied  the  Irishman. 


ENGINES  67 

"Oh !  I'm  not  talking  about  street  cars,"  testily  replied 
McAndrew.  "There  are  certain  substances  which  transmit 
heat  very  readily,  and  they  are  termed  'conductors' ;  others 
which  transmit  heat  very  slowly  are  known  as  'non-con- 
ductors.' It  is  often  said  that  man  cannot  improve  upon 
nature,  and  this  is  verified  by  the  fact  that  hair-felt,  made 
principally  of  cow  hair  or  horse  hair,  is  about  the  best  non- 
conductor we  can  use.  Hair-felt  will  burn  or  scorch  if  placed 
on  surfaces  which  are  too  hot,  such  as  the  cylinders  of  an 
engine  using  high-pressure  steam,  hence  combinations  of 
asbestos  and  magnesia  make  the  best  non-conductors  for  that 
purpose. 

"The  next  parts  of  a  marine  engine  to  be  considered  are 
the  pistons  and  piston  rods.  The  pistons  are  made  either  of 
cast  iron  or  cast  steel ;  sometimes  for  lightness,  as  in  the  case 
of  those  used  in  torpedo  boat  engines,  they  are  made  of 
wrought  steel.  If  they  are  made  flat  and  of  box  section,  that 
is,  with  double  walls,  the  material  used  is  cast  iron.  However, 
the  majority  of  pistons  are  cast  solid  of  conical  section  to 
provide  the  necessary  strength,  and  in  this  shape  are  almost 
invariably  of  cast  steel.  In  first-class  work  they  should  be 
machined  all  over,  so  as  to  reduce  the  clearance  spaces  as 
much  as  possible.  It  is  necessary,  410  matter  what  the  type 
of  piston  used,  to  provide  some  means  of  preventing  the 
steam  from  leaking  past  the  piston.  This  is  accomplished  by 
rings  fitted  in  grooves  in  the  rim  of  the  piston,  which  either 
from  their  natural  elasticity  or  from  being  forced  outward  by 
springs  of  various  forms,  keep  tight  against  the  wall  of  the 
cylinder  and  prevent  the  leakage  of  steam.  These  rings  are 
always  made  of  cast  iron,  as  no  other  metal  will  suffice.  Great 
care  is  usually  taken  to.  prevent  the  steel  pistons  from  wear- 
ing against  the  sides  of  the  cylinders,  as  steel  on  iron  is  a  bad 
combination  where  the  surfaces  are  not  thoroughly  lubricated. 

"The  piston  rods,  which  transmit  the  motion  of  the  pistons 


68  MC  ANDREW'S    FLOATING    SCHOOL 

to  the  crossheads,  are  simply  cylindrical  columns,  securely 
fastened  to  the  pistons  at  the  top  and  the  crossheads  at  the 
bottom,  by  means  of  fitting  into  tapered  holes,  whictt  take  up 
the  thrust  in  one  direction  and  nuts  which  prevent  movement 
in  the  other  direction.  Piston  rods  are  almost  invariably  made 
of  wrought  steel,  and  to  save  weight  are  sometimes  made 
hollow.  Now  I  think  I  heard  one  of  you  fellows  say,  some- 
time ago,  that  a  hollow  piston  rod  is  stronger  than  a  solid 
one,  or  was  it  a  hollow  shaft  you  were  talking  about?  Any- 
how, you  want  to  forget  that,  as  I  find  too  many  people  get 
that  foolishness  in  their  minds.  A  hollow  rod  or  a  hollow 
shaft  is  stronger  than  a  solid  one  of  the  same  weight,  that  is 
of  the  same  amount  of  metal  used,  but  you  can  see  that  if  only 
the  same  amount  of  metal  is  used  the  solid  rod  or  shaft  will 
be  of  a  smaller  diameter.  So  hereafter  you  can  say,  for 
example,  that  a  6-inch  hollow  rod  with  a  3-inch  hole  through 
it  is  not  as  strong  as  a  6-inch  solid  rod,  but  that  it  is  stronger 
than  a  5^-inch  solid  rod  which  contains  the  same  amount  of 
metal.  Even  then  it  is  only  stronger  when  the  rod  is  being 
pressed  down  or  in  compression,  as  it  is  called ;  when  it  is 
being  pulled,  or  is  in  tension,  it  would  be  of  the  same  strength, 
whether  hollow  or  solid,  as  there  would  be  the  same  sec- 
tional amount  of  metal  to  transmit  the  pull." 

"Why  don't  they  make  piston  rods  square  instead  of  round?" 
inquired  the  studious  Nelson. 

"I'm  glad  you  spoke  of  that,"  replied  the  instructor.  "So 
far  as  actually  transmitting  the  work  is  concerned  I  sup- 
pose a  square  rod  would  do  as  well  as  a  round  rod,  but  the 
rod  must  pass  through  the  bottom  of  the  cylinder  so  as  not  to 
allow  the  steam  to  escape.  It  would  be  very  difficult  indeed  to 
build  a  stuffing-box  around  a  square  rod  and  keep  it  tight, 
whereas  with  a  round  rod  it  is  comparatively  simple.  Another 
reason  is  that  it  is  much  cheaper  to  machine  a  round  rod 
than  it  is  a  square  one.  In  passing  it  will  be  well  to  consider 


ENGINES  69 

the  manner  in  which  steam  is  prevented  from  leaking  out  of 
the  cylinders  around  the  piston  rods  and  valve  stems.  In  the 
olden  days  when  the  steam  pressures  and  consequent  tem- 
peratures were  low,  it  was  quite  an  easy  matter  to  keep  rods 
tight  by  a  simple  stuffing-box  with  an  adjustable  gland,  packed 
with  hemp  or  other  form  of  soft  packing.  Nowadays  the 
steam  pressures  and  temperatures  are  so  high  that  they  would 
soon  burn  or  blow  out  hemp  packing,  and  the  result  is  that 
metallic  packing  has  to  be  used.  This  has  been  a  fertile  field  for 
the  inventor,  with  the  result  that  almost  every  day  a  chief  en- 
gineer, when  in  port,  will  be  met  by  a  man  with  a  new  kind 
of  packing,  guaranteed  to  be  better  than  any  other  kind  ever 
made  and  capable  of  saving  at  least  10  percent  in  the  coal 
bills.  Metallic  packing  usually  consists  of  rings  of  cast  iron, 
white  metal  or  composition,  held  against  the  rod  by  the  com- 
pression of  springs  of  ingenious  forms.  The  best  of  them  is 
the  one  that  keeps  the  rod  the  tightest  with  the  least  amount 
of  friction." 

"What  kind  is  that?"  said  O'Rourke. 

"You  can  search  me,"  replied  McAndrew.  "Now,  having 
described  the  principal  features  of  cylinders,  we  must,  in 
regular  order,  find  what  they  stand  on,  or  what  it  is  that 
supports  them,  as  you  all  know  that  the  cylinders  must  be 
held  in  place  as  rigidly  as  possible. 

"What  name  is  given  to  these  supports,  O'Rourke?" 

"  'Colyums,'  sir !"  replied  the  one  addressed. 

"Oh !  you  are  learning  fast,"  said  the  instructor,  "nearly 
all  old-timers  refer  to  them  as  'col-yums'  instead  of  'col-umns,' 
as  the  word  should  properly  be  pronounced. 

"Columns  are  made  of  numerous  designs — of  cast  iron, 
cast  steel  and  wrought  steel.  Some  engines  are  supported  on 
cast  iron  box-section  columns  at  front  and,  back,  but  I  think 
the  majority  of  marine  engines  have  cast  iron  inverted 
Y-columns  at  the  back  and  cylindrical  wrought  steel  columns 


7o  MC  ANDREW'S   FLOATING'  SCHOOL 

at  the  front,  as  shown  in  Fig.  6,  where  sections  are  shown 
also.  In  nearly  all  merchant  vessels'  engines  the  condenser 
is  built  in  the  engine  frame  and  forms  a  part  of  the  support 
for  the  cylinders.  Short  columns,  to  which  the  guides  are  at- 
tached, are  bolted  to  the  top  of  the  condenser." 

"I  thought  guides  were  men  who  show  'rubes'  around  the 


FIG.    6. INVERTED    Y    AND    CYLINDRICAL    COLUMN 

city;  how  do  they  get  in  on  this  engine  game?"  inquired  the 
'butter-in'  of  the  class. 

"On  a  marine  engine,"  replied  McAndrew,  "the  guides  show 
the  crosshead  slippers  how  to  walk  the  straight  and  narrow 
path ;  if  they  permitted  them  to  roam  around  very  much 
there  would  be  trouble.  In  that  respect  they  differ  from  the 
average  two-legged  guide  such  as  you  have  met  on  shore. 

"The  guides  shown  in  the  above  sketch  attached  to  the 
Y-columns  are  the  kind  used  most  extensively  for  marine 


ENGINES  71 

work.  When  the  engine  is  backing,  the  pressure  on  the  guides 
is  in  the  direction  opposite  from  that  when  it  is  going  ahead, 
so  this  pressure  is  overcome  by  what  are  known  as  'backing 
guides,'  which  are  shown  in  section  C-D.  The  space  back  of 
the  'go-ahead'  guide  is  usually  fitted  for  water  circulation, 
whereby  the  cold  sea  water  flowing  through  removes  the  heat 
caused  by  the  friction  on  the  rubbing  surfaces.  Marine 


n 

1 

1  \ 

l; 

[j 

>T            < 

V 

I  / 

FIG.     7. CONNECTING     ROD 


engines  back  so  little  of  the  time  that  it  is  seldom  necessary 
to  fit  the  'backing  guides'  for  water  circulation. 

"On  our  way  down  the  engine  we  next  come  to  the  connect- 
ing rod,  by  means  of  which  the  up-and-down  or  reciprocating 
motion  is  transformed  into  a  circular  or  rotary  motion  by 
means  of  the  crank.  Perhaps  Schmidt  can  tell  us  the  German 
name  for  connecting  rod." 

"Sure !"  said  Schmidt.  "In  the  old  country  they  call  it  the 
'verbindungstikken.' " 

"Gee !  "chimed  in  O'Rourke,  "that's  about  as  long  as  the  rod 
itself!" 


72  MC  AN  DREW'S     FLOATING     SCHOOL 

"Yes,  the  word  is  rather  long,  and  it  means,  literally,  a 
binding  stiek,  because  it  binds  or  connects  the  crosshead  to 
the  crankpin.  These  rods  are  almost  invariably  forged  of 
mild  open-hearth  steel.  Fig.  7  illustrates  the  type  in  most 
general  use. 

"The  upper  end,  as  you  will  see,  is  forked  to  span  the 
crosshead,  each  side  of  .the  fork  being  fitted  with  a  bearing 
and  the  necessary  connections  to  work  on  the  crosshead  pin. 
Solid  brass  or  bronze  is  used  for  the  bearing  metal,  as  the 
pressure  is  too  great  to  permit  of  the  use  of  soft,  anti-friction 
metal  in  the  bearings.  The  lower  end  of  the  connecting  rod 
is  provided  with  brasses  and  a  cap  or  binder,  all  secured  by 
bolts  to  the  T-shaped  end  of  the  connecting  rod.  These 
brasses  are  always  fitted  with  'Babbitt'  or  other  anti-friction 
metal  to  reduce  the  rubbing  friction  on  the  crankpin.  The 
white  metal  surfaces  are  scored  with  oil  grooves  to  allow  a 
proper  distribution  of  the  lubricating  oil.  Bearings,  such  as 
crosshead  and  crankpin  brasses,  necessarily  are  subject  to 
wear,  and  consequently  must  be  provided  with  means  of  taking 
up  the  lost  motion.  To  that  end  there  are  spaces  between  the 
top  and  bottom  brasses  in  which  are  fitted  distance  pieces  of 
composition  and  a  varying  number  of  strips  of  thin  sheet  brass 
or  tin  called  'shims,'  which,  when  removed,  take  up  the  lost 
motion  due  to  the  wear  on  the  brasses.  Later  on  I  will  de- 
scribe to  you  the  method  of  adjusting  crosshead  and  con- 
necting rod  brasses,  which  constitutes  one  of  the  most  import- 
ant of  the  many  duties  which  befall  the  marine  engineer. 

"The  crankshaft  is  the  member  that  actually  turns  the  pro- 
peller, and  hence  is  the  connection  between  the  producer  and 
the  consumer  of  the  power,  or  the  middleman,  as  they  would 
tell  you  in  business  circles." 

"He's  the  guy  that  causes  the  high  cost  of  living;  but  I 
never  heard  him  called  a  crank  before,"  suggested  O'Rourke. 

"Anyhow,   the  crankshaft  is  a  very    important  part  of   an 


ENGINES 


73 


engine,"  continued  McAndrew.  "Nearly  all  crankshafts  are 
forged  of  mild  open-hearth  steel,  but  some  still  are  built-up 
forgings  of  wrought  iron.  In  some  high-class  marine  work 
the  crank  for  each  cylinder  is  forged  in  one  solid  piece,  such 
as  shown  in  Fig.  8. 


FIG.    8. SECTION    OF    FORGED    CRANKSHAFT 


FIG      9.— SECTION    OF    BUILT-UP    CRANKSHAFT 


"The  advantage  of  a  crankshaft  of  this  kind  is  that  the  sec- 
tions are  interchangeable,  so  that,  for  instance,  if  the  low- 
pressure  crankpin  should  break  the  high-pressure  crank  could 
be  put  in  its  place  and  the  engine  run  compound— that  is,  if 
the  engine  was  of  the  triple-expansion  type.  The  built-up 
crankshaft  is,  as  its  name  indicates,  composed  of  several 
parts,  the  slabs  being  shrunk  and  keyed  onto  the  crank  pins 
and  sections  of  the  shaft  as  shown  in  Fig.  9." 


74 


MC  ANDREW  S     FLOATING     SCHOOL 


"Why  do  some  crankshafts  have  holes  in  them?"  inquired 
Pierce. 

"That  is  done  in  high-class  work  for  two  principal  reasons. 
One  is  that  it  saves  weight  and  the  other  is  that  in  making 
large  forgings  of  this  kind  most  of  the  imperfections,  or 
'pipes,'  as  they  call  them,  are  liable  to  be  in  the  central  part 


FIG.    10. BEDPLATE    FOR    TRIPLE-EXPANSION    ENGINE    IN    ONE    CASTING 

of  the  forging.     Making  the  shaft  hollow   either  removes  the 
imperfections  or  exposes  them  to  the  view  of  the  inspector. 

"As  I  told  you  in  the  case  of  the  piston  rod,  a  hollow  shaft 
is  not  stronger  than  a  solid  shaft,  as  many  young  men  im- 
agine ;  it  is  simply  stronger  than  a  solid  shaft  containing  the 
same  amount  of  metal.  To  transmit  a  twisting  strain  the 
metal  on  the  outside  of  the  shaft  counts  much  more  than 
metal  at  the  center.  For  example,  take  a  shaft  10  inches  in 
diameter;  the  outer  portion  of  the  metal — only  .16  inch  in 
thickness — is  of  as  much  service  in  transmitting  torsional  or 
twisting  strains  as  the  metal  5  inches  in  diameter  at  the 
center  of  the  shaft.  Perhaps  it  will  give  you  a  better  idea  of 
what  I  am  getting  at  to  state  that  a  shaft  16  inches  in  diameter, 
having  a  lo-inch  hole  through  it,  is  equal  in  strength  to  a  solid 
shaft  15  inches  in  diameter  made  of  the  same  kind  of  metal. 


ENGINES  -5 

"Further  advantages  of  hollow  crank  pins  are  that  in  case  of 
a  pin  breaking  it  could  be  repaired  temporarily  by  fitting  a 
large  bolt  through  the  hole,  which  would  allow  the  engine  to 
foe  run  slowly  at  least;  the  hole  through  crank  pins  is  also  used 
to  advantage  in  some  engines  to  permit  of  the  fitting  of  cen- 
trifugal oiling  devices. 

"The  bed-plate  is  the  part  of  the  engine  which  supports  the 
weight  of  the  entire  structure,  and  also  forms  the  seating  for 


FIG^-ll. DETAILS    OF    BEDPLATE    IN    FIG.    10.       SECTIONS    SHOWING   MAIN 

PILLOW    BLOCK 


the  crankshaft  or  main  bearings.  They  are  usually  made  of 
cast  iron  and  sometimes  of  cast  steel,  and  consist  of  a  series 
of  athwartship  girders,  one  under  each  crankshaft  bearing,  all 
being  joined  by  fore-and-aft  girders,  one  on  each  side.  Natur- 
ally, they  are  made  as  heavy  and  substantial  as  possible.  The 
ibed-plate  is  secured  to  the  foundation,  an  integral  part  of  the 
ship's  structure,  by  means  of  holding-down  bolts.  Fig.  10 
will  show  you  an  ordinary  type  of  bed-plate  and  Fig.  n  a 
main  bearing,  or  'pillow  block,'  as  it  is  sometimes  called. 

"The  main  bearing  shown  in  this  sketch  is  such  as  used  for 
small  engines.  On  larger  engines  the  bottom  brass  and  the 
cap  or  binder,  as  the  top  bearing  is  called,  are  usually  cored  to 


76  MC  ANDREW'S    FLOATING    SCHOOL 

allow  for  the  circulation  of  sea  water  in  order  to  prevent  the 
bearing  from  becoming  unduly  heated  when  the  engine  is  run 
at  full  speed.  All  main  bearings  are  lined  with  Babbitt  or 
other  anti-friction  metal  to  reduce  the  friction." 


CHAPTER  X 
Valves  and  Valve  Gear 

"Having  gone  over  the  principal  parts  of  the  engine,  we  will 
now  take  up  some  of  the  miner  parts,  the  principal  one  of 
which  is  the  valve  gear. 

"It  is  highly  important  to  allow  the  steam  to  enter  the 
cylinder  at  the  right  time,  and  it  is  equally  as  important  to  let 
it  out  at  the  right  time.  These  operations  must  necessarily  be 
performed  automatically.  The  story  is  told  that  in  the  first 
engine  built  by  James  Watt,  which  was,  of  course,  a  very 
crude  affair,  he  had  not  progressed  far  enough  in  his  design 
to  have  the  valve  operated  by  the  engine  itself,  and,  in  con- 
sequence, a  boy  was  employed  to  lift  the  valve  and  close  it  at 
about  as  near  the  proper  time  as  his  limited  training  and 
judgment  would  allow.  Evidently  tiring  of  such  monotonous 
employment,  and  being  of  an  ingenious  turn  of  mind,  he 
noticed  that  a  certain  part  of  the  engine  mechanism  had  about 
the  same  motion  which  he  imparted  to  the  valve  and  at  about 
the  same  time.  Consequently,  as  the  story  goes,  he  tied  a 
stout  piece  of  cord  to  the  valve  lever  and  connected  it  to  the 
part  of  the  engine  which  had  the  coincident  motion,  where- 
upon the  valve  was  actuated  automatically,  and  the  boy  was 
found  by  his  employer  out  in  the  yard  playing  marbles,  civil- 
ization having  not  advanced  sufficiently  far  at  that  remote 
period  to  permit  of  the  youngster  indulging  in  the  more  scien- 
tific game  of  shooting  craps. 

'That  boy  unconsciously  formed  the  first  valve  gear  ever 
put  on  an  engine,  but  since  his  time  there  has  been  consider- 


78  MC  ANDREW  S     FLOATING     SCHOOL 

able  improvement  in  the  method  of  actuating  valves.  Before 
describing  any  methods  for  moving  the  valve,  you  had  first 
better  be  given  an  idea  of  the  valve  itself.  There  are  a  number 
of  different  kinds  of  valves  used  on  stationary  engines,  but 
for  marine  engines  there  is  practically  but  one  type  used,  and 
that  is  known  as  the  slide  valve. 

"There  are  two  principal  types  of  slide  valve :  the  flat  D  and 
the  piston  valve.  The  simplest  kind  of  a  flat  D  slide  valve  is 
like  Fig.  12. 


FIG.    12. PLAIN    SLIDE    VALVE,    MID-POSITION 


'This  valve,  by  sliding  back  and  forth  over  the  valve  seat, 
alternately  admits  and  releases  steam  to  and  from  the  cylin- 
der which  drives  the  piston  up  and  down.  In  Fig.  12 
the  valve  is  shown  in  what  is  known  as  its  mid-position.  The 
amount  which  the  valve  overlaps  the  steam  port  in  this  posi- 
tion, A  B,  is  known  as  the  'lap'  of  the  valve,  and  you  must  fix 
that  in  your  memory,  as  it  is  frequently  referred  to  by  all 
marine  engineers.  There  are  two  kinds  of  lap,  as  you  will 
notice  that  on  the  inside  of  the  valve  it  also  extends  over  the 
port  the  distance  C  D.  The  outside  lap,  A  B,  is  known  as  the 
'steam  lap,'  and  the  inside  lap,  C  D,  is  the  'exhaust  lap.' 

"In  Fig.  13  the  valve  is  shown  at  the  end  of  its  stroke, 
and  you  will  notice  that  the  valve  has  opened  one  of 
the  steam  ports  on  the  outside  a  distance,  A  B;  this  is  known 
as  'lead,'  and  there  are  two  kinds  of  lead  also;  the  outside,  or 


VALVES     AND     VALVE    GEAR  79 

A  B,  being  known  as  the  'steam  lead,'  and  the  inside,  or  C  D, 
being  known  as  the  'exhaust  lead.'  " 

"Chief,  that  sounds  like  horse  race  dope,  the  kind  I  used  to 
hear  down  at  Brighton  Beach,"  said  O'Rourke.  "I  suppose 
you  will  be  telling  us  next  that  the  high-pressure  valve  is  in 
the^  lead — one  lap  ahead  of  the  low-pressure." 

"No  doubt,  young  man,  you  know  more  about  horse  race 
dope  than  you  do  of  anything  else ;  but  this  is  no  place  for  such 
silly  remarks,"  tartly  rejoined  Me  Andrew. 

"Why  does  a  valve  have  this  lap  ?"  inquired  Nelson. 

"There  is  some  sense  to  a  question  like  that,"  said  the  in- 
structor. "Lap  is  given  to  a  valve  so  that  the  steam  can  be 


FIG.  13. PLAIN     SLIDE    VALVE.     POSITION     FOR     END    OF    STROKE 

cut  off  at  a  portion  of  the  stroke  and  be  allowed  to  expand 
in  the  cylinder.  If  the  valve  was  made  the  same  over-all 
length  as  the  distance  between  the  outer  edges  of  the  two 
steam  ports,  live  steam  from  the  boiler  would  be  allowed  to 
follow  the  piston  nearly  the  entire  stroke,  and  we  would 
gain  nothing  from  the  expansive  effect  of  the  steam. 

"As  the  piston  nears  the  end  of  its  stroke,  a  certain  amount 
of  the  exhausting  steam  in  the  end  of  the  cylinder  towards 
which  the  piston  is  traveling  is  retained,  and  as  it  cannot 
escape  it  is  compressed  and  forms  a  cushion,  which  overcomes 
the  momentum  of  the  piston,  rod,  etc.  As  this  is  generally  in- 
sufficient to  overcome  so  much  momentum,  the  live  steam'  for 
the  return  stroke  is  admitted  prior  to  the  time  when  the 


8o  MC  ANDREW'S    FI/JATING    SCHOOL 

piston  starts  on  its  return.  The  amount  the  steam  valve  is 
open  at  the  very  commencement  of  the  return  stroke  is,  as 
before  stated,  known  as  'lead,'  the  purpose  of  which  is  to  aid 
in  quickly  overcoming  the  momentum  of  the  moving  parts  and 
to  start  the  piston  back  quickly  on  its  return. 

"Some  old-fashioned  simple  and  compound  engines  are 
furnished  with  a  cut-off  valve  separate,  and  working  upon  the 
back  of  the  regular  valve  in  order  to  get  a  sufficient  amount 
of  expansion  of  the  steam,  but  in  triple  or  quadruple-expansion 
engines  we  do  not  need  to  cut  off  closely  in  the  high-pressure 
cylinder,  as  there  are  three  or  four  cylinders  in  which  the 
expansion  may  take  place.  A  double-ported  slide  valve  is  one 
used  when  it  is  desired  to  get  a  very  large  port  opening  for  a 
comparatively  short  valve  travel;  it  is  practically  one  valve 
within  another,  and  there  are  two  steam  ports  instead  of  one 
in  the  valve  seat,  the  steam  for  the  outside  ports  entering  over 
the  ends  of  the  valve  and  the  steam  for  the  inner  ports  coming 
through  passageways  in  the  sides  of  the  valve.  On  nearly  all 
large  cylinders  it  is  found  necessary  to  use  these  double-ported 
valves,  or  otherwise  the  valve  travel  would  be  entirely  too 
great. 

"The  great  disadvantage  in  using  the  flat  slide  valve  is  the 
large  amount  of  power  consumed  in  overcoming  the  friction 
between  the  valve  and  its  seat.  For  instance,  a  slide  valve  of 
ordinary  size  would  be,  perhaps,  30  inches  long  by  42  inches 
wide,  a  flat  surface  of  1,260  square  inches.  At  only  40  pounds 
pressure  per  square  inch  in  the  steam  chest  there  would  be  a 
pressure  of  over  50,000  pounds  pressing  the  valve  against  the 
valve  seat-  You  can  readily  imagine  that  the  friction  caused 
by  moving  iron  against  iron  with  such  a  load  as  that  is 
enormous.  Therefore,  flat  slide  valves  are  not  used  to  any 
great  extent  nowadays  except  in  small  engines,  and  then  only 
for  the  low-pressure  cylinder,  where  the  initial  pressure  of  the 
steam  entering  the  cylinder  is  usually  not  over  5  to  10  pounds. 


VALVES     AND     VALVE     GEAR 


81 


"Some   wise   old-timer,   to   get  away  from  using   flat   slide 
valves,  conceived  the  idea  of  wrapping  up  his  slide  valve  into 


FIG.    14. PISTON   V.ALVE 

the  form  of  a  cylinder,  and  thereby  removing  all  unbalanced 
pressure  from  the  valve  while  retaining  the  advantages  of  .the 
slide  valve.  Its  essential  features  are  two  pistons  or  heads 


82  MC  ANDREW'S   FLOATING   SCHOOL 

joined  by  an  intermediate  distance  piece,  all  being  held  in 
place  on  the  valve  stem  by  nuts  and  washers,  as  shown 
in  Fig.  14. 

"The  steam  is  admitted  and  exhausted  to  and  from  the 
cylinder  by  the  edges  of  the  valve  in  precisely  the  same  manner 
as  the  flat  slide  valve.  The  only  disadvantage  is  the  excessive 
clearance  as  compared  with  the  flat  valve." 

"What's  clearance,  Chief?"  remarked  Nelson. 

"The  clearance  space  in  an  engine  is  the  volume  of  the  steam 
ports  and  passageways  between  the  piston  and  the  bottom  and 
top  heads  of  the  cylinder.  It  would  never  do  to  have  the 
moving  piston  strike  the  head,  either  at  the  bottom  or  top,  for 
if  it  did  it  would  knock  them  off.  Consequently  there  is 
usually  a  space  of  about  l/^  inch  at  the  top  and  ^  inch  at  the 
bottom,  always  more  at  the  bottom  to  allow  for  the  bearings 
wearing  down.  These  distances  are  known  as  the  linear  clear- 
ances, while  the  entire  volume  of  the  space  between  the  piston 
at  the  end  of  its  stroke  and  the  cylinder  head,  plus  the  volume 
of  the  steam  passageways,  is  known  as  the  volumetric  clear- 
ance. Naturally,  as  the  ports  have  to  reach  clear  around  the 
piston  valve,  there  is  more  of  this  volumetric  clearance  for 
this  type  than  there  is  for  a  flat  valve  which  lays  close  up 
to  the  cylinder.  In  modern  engine  designs  this  volume  is 
considerably  decreased  by  making  the  ports  straight  instead  of 
curved,  as  shown  in  the  sketch. 

"Piston  valves  can  be  kept  tighter  than  flat  slide  valves,  for 
the  reason  that  it  is  usual  to  fit  the  two  pistons  composing  the 
valve  with  packing  rings  similar  to  those  used  for  the  main 
pistons. 

"We  have  looked  into  the  principal  kinds  of  valves  used  on 
marine  engines  and  know  what  functions  they  perform,  now 
we  want  to  know  what  kind  of  apparatus  it  is  that  moves  the 
valves.  There  are  three  principal  types  of  operating  gear  used 
on  marine  engines,  known  by  the  names  of  the  inventors,  re- 
spectively, as  'Stephenson,'  'Joy'  and  'Marshall.' 


VALVES  AND  VALVE  GEAR  83 

"The  Stephenson  gear  is  probably  used  on  over  90  percent 
of  the  marine  engines  in  use.  If  ship's  engines  had  to  travel 
in  one  direction  only,  the  valve  mechanism  would  be  com- 
paratively simple,  but  engines  of  this  kind,  as  well  as  those  on 
locomotives,  have  to  be  reversed  frequently,  so  it  is  neces- 
sary to  have  the  valve  gear  designed  so  that  it  can  go  either 
ahead  or  back. 

"This  condition  was  quite  readily  solved  by  Stephenson, 
one  of  the  first  engineers,  when  he  invented  his  link  gear.  In 
this  mechanism  the  fundamental  motion  is  taken  from  the 


FIG.     15. PLAIN     ECCENTRIC,    SKELETON    MOTION 

crankshaft  by  means  of  eccentrics  keyed  to  the  shaft.  Per- 
haps O'Rourke  can  tell  us  the  difference  between  an  eccentric 
and  a  crank." 

"That's  easy,"  replied  the  ever-ready.  "If  a  rich  man  does 
queer  things  he  is  an  eccentric,  but  if  a  poor  man  does  the 
same  stunts  everybody  calls  him  a  crank." 

"Well,  that  brings  out  the  idea,  anyhow,"  continued  McAn- 
drew.  "There  is  in  reality  very  little  theoretical  difference 
between  an  engine  eccentric  and  a  crank,  as  an  eccentric  is 
practically  a  self-contained  crank.  The  term  'eccentric'  means 
literally  'having  different  centers,'  whereas  'concentric'  means 
having  the  same  centers.  Hence  it  is  that  the  center  of  the 
sheave,  forming  the  eccentric,  is  set  off  from  the  center  of 
the  shaft  upon  which  it  operates,  a  distance  which  is  known  as 
the  'eccentricity'  or  'throw.'  The  following  will  illustrate  the 
idea  of  the  eccentric : 


84 


MC  ANDREW  S    FLOATING    SCHOOL 


"The  distance  A  C,  Fig.  15,  between  the  center  of  the  shaft 
and  that  of  the  sheave  is  the  throw,  and  the  up-and-down  mo- 
tion imparted  to  the  valve,  or  the  valve  travel,  as  it  is  known, 
is  double  this  throw.  Around  the  eccentric  sheave  is  fitted  a 
band  or  strap,  as  it  is  termed,  made  in  halves  and  bolted  to- 
gether, which  strap  is  bolted  to  the  heel  of  the  eccentric  rod. 
This  rod  is  forked  at  its  upper  end  and  spans  one  end  of  the 


rm 

3 

3        3 

rrn 

i 

1      0 

o       0    |   | 

1  _!  1 

H 

i    ,  ... 

~T 

i 

/f^TTvh  '  '  ~~  

1  ^ 

M^. 

f 
F 

1      O 

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f..:.-))O    1    1 

u       HJ 

Fin 


FIG.     16. STEPHENSON     DOUBLE     BAR    LINK 

link.  There  are  two  eccentrics  and  all  the  necessary  con- 
nections for  each  cylinder,  one  known  as  the  'go-ahead'  and 
the  other  as  the  'backing'  eccentric.  The  go-ahead  eccentric 
rod  connects  with  one  end  of  the  link  and  the  backing  eccen- 
tric rod  with  the  other  end. 

"Almost  all  links  for  large  engines  are  of  the  double-bar 
type ;  that  is,  they  are  built  up  of  two  parallel  steel  bars,  each 
forming  the  arc  of  a  circle,  the  radius  of  which  is  equal  to  the 
distance  between  the  center  of  the  eccentric  sheave  and  the 
center  line  of  the  bars. 


VALVES  AND  VALVE  GEAR  85 

"You  will  notice  the  mechanism  in  the  center  of  the  link. 
That  is  known  as  the  link  block,  and  it  forms  the  connection 
between  the  link' and  the  valve  stem.  In  operation  the  links 
are  thrown  from  one  side  to  the  other,  so  that  the  link  block 
is  actuated  by  either  the  go-ahead  eccentric  or  the  backing 
eccentric,  as  may  be  desired,  by  placing  the  link  block  in  line 
with  either  of  these  eccentric  rods. 

"Eccentric  sheaves  are  always  made  of  cast  iron,  in  two 
unequal  halves,  in  order  to  bring  the  joint  between  them  on 
the  center  line  of  the  shaft,  so  that  they  can  be  readily  re- 
moved. 

"The  eccentric  straps  which  ride  on  the  sheaves  are  also 
made  in  halves,  bolted  together,  and  are  usually  of  cast  iron  or 
cast  steel,  lined  with  white  metal  in  order  to  reduce  the 
friction. 

"Eccentric  rods  and  link  bars  are  usually  made  of  wrought 
steel  of  the  best  quality.  The  link  blocks  are  usually  of 
forged  steel,  fitted  with  composition  wearing  pieces  where  they 
rub  on  the  link  bars.  Sometimes  they  are  cast  entirely  of 
bronze. 

"To  reverse  an  engine,  that  is,  to  change  it  from  the  ahead 
motion  to  the  backing  motion,  or  vice  versa,  there  is  provided 
a  rock  shaft,  which  extends  along  the  engine  columns,  and  to 
which  it  is  supported  in  brackets.  On  this  rock  shaft  there  is 
secured  for  the  valve  gear  of  each  cylinder  a  lever,  or  re- 
versing arm,  as  it  is  called.  This  arm  connects  to  the  valve 
gear  links  by  suspension  or  bridle  rods,  as  they  are  sometimes 
called.  This  rock  shaft  on  small  engines  is  operated  by  hand 
through  the  medium  of  a  long  lever,  or  in  some  cases  by  a 
large  hand-wheel  and  screw.  However,  this  means  is  not 
practicable  for  larger  engines,  as  it  would  require  more  power 
than  a  man  could  apply.  Hence  all  large  marine  engines  are 
fitted  with  what  is  known  as  a  reversing  engine,  which. con- 
sists of  a  steam  cylinder,  the  piston  rod  of  which  is  connected 


86 


MC  ANDREW  S    FLOATING    SCHOOL 


by  means  of  links  to  the  reverse  arm  on  the  rock  shaft. 
Fig.  17  will  show  you  details  of  an  ordinary  reversing  engine. 
"The  valve  of  this  steam  cylinder  is  controlled  by  what  is 
termed  a  'floating  lever,'  the  initial  motion  being  given  it  by 
means  of  the  hand  reversing  lever  located  at  the  working 
platform.  A  small  slide  valve  of  either  the  flat  slide  or  the 


FIG.  17. FLOATING  LEVER  REVERSE  GEAR 

piston  slide  type  controls  the  admission  of  the  steam  to  the 
cylinder.  Unless  the  lever  at  the  working  platform  is  handled 
by  an  experienced  man,  the  piston  is  liable  to  go  forward  or 
backward  with  a  rush,  causing  the  gear  to  slam.  To  avoid  any 
damage  being  done  it  is  customary  to  fit  strong  spiral  springs 
at  each  end  of  the  crosshead  guide  rod  to  prevent  slamming." 


CHAPTER  XI 

Engine  Fittings 

"As  we  look  into  the  fittings  which  go  on  a  boiler  we  should 
also  pay  some  attention  to  what  are  known  as  engine  fittings. 

"The  principal  of  these  is  the  throttle  valve,  by  means  of 
which  the  engine  is  started  or  stopped  at  will.  It  is  custom- 
ary to  bolt  the  throttle  direct  to  the  high-pressure  valve  chest, 
and  to  operate  it  by  means  of  a  lever  and  rods  from  the  work- 


FIG.     18. DOUBLE    BEAT    POPPET    VALVE 

ing  platform.  The  most  generally  used  type  of  throttle  valve 
is  known  as  the  double-beat  valve,  the  general  principles  of 
which  are  shown  in  Fig.  18. 

'This  is  really  two  valves  in  one,  the  steam  entering  through 
two  openings  in  the  valve  casing.  The  two  disks  are  worked 
on  one  stem,  the  upper  disk  being  made  slightly  larger  than 
the  lower  one,  so  that  the  tendency  is  always  to  close  the  valve. 
However,  this  difference  in  the  load  on  the  two  disks  is  so 
slight  that  it  can  readily  be  overcome  by  means  of  the  throttle- 
working  lever.  This  lever  works  on  a  notched  quadrant,  and 


88  MC  ANDREW'S  FLOATING  SCHOOL 

it  is  held  in  position  by  means  of  a  spring  latch.  In  practical 
working  of  a  throttle  you  will  find  that  it  only  needs  to  be 
opened  a  very  slight  amount  in  order  to  work  the  engine  'to 
bells/  as  it  is  termed. 

"Right  here  it  may  be  well  to  inform  you  that  a  valve  does 
not  have  to  be  opened  very  far  to  secure  a  full  opening,  or  to 
have  it  'wide  open/  as  the  term  is.  A  little  figuring  will  illus- 
trate the  idea.  For  example,  if  you  are  using  a  throttle  10 
inches  in  diameter,  its  total  area  is  10  by  10  by  .7854  =  78.54 
square  inches.  That  is,  to  find  the  area  of  a  circle  you  multiply 
the  diameter  by  itself,  or  square  it,  as  the  mathematicians 
would  tell  you,  and  then  multiply  that  product  by  the  constant 
.7854.  To  find  the  circumference  of  a  circle  you  multiply  the 
diameter  by  the  constant  3.1416.  This  last  constant  is  known 
as  'pi';  now  don't  be  alarmed,  O'Rourke,  for  that  is  not  the 
kind  you  eat,  it  is  simply  the  Greek  letter  that  is  selected  to 
represent  the  ratio  between  the  diameter  and  circumference 
of  a  circle.  The  circumference  of  a  lo-inch  circle  is  31.416 
inches.  Dividing  78.54,  the  area  in  square  inches,  by  the 
length  of  the  circumference,  31.416  inches,  you  will  find  the 
answer  to  be  2.5.  In  other  words,  a  lo-inch  throttle  valve 
has  to  be  opened  only  2^  inches  to  be  wide  open.  You  should 
also  note  that  2^2  is  just  one-fourth  of  10,  and  bearing  in 
mind  that  the  ratio  between  the  circumference  and  diameter 
of  all  circles  is  the  same,  you  will  see  that  any  valve  has  to 
be  raised  only  a  distance  equal  to  one-quarter  its  diameter  to 
be  'wide  open.' 

"Most  valves  are  designed  to  allow  a  larger  opening,  but  you 
will  see  from  the  illustration  that  it  is  not  necessary  to  jam 
a  valve  open  as  far  as  it  will  go  in  order  to  get  the  full  area 
through  it." 

"Isn't  it  possible  to  get  a  triple-expansion  engine  stuck  on 
a  center?"  asked  Pierce. 

"Yes,  it  is  not  only  possible  but  it  occurs  quite  frequently," 


ENGINE   FITTINGS  89 

answered  McAndrew.  "To  avoid  trouble  of  this  kind  all 
compound  and  triple-expansion  engines  are  fitted  with  what 
afe  termed  'pass-over  valves.'  " 

"That  must  be  a  Jew  valve !"  suggested  O'Rourke. 

"This  is  hardly  that  kind  of  a  valve,"  continued  the  in- 
structor. "The  necessity  for  such  a  valve  occurs  when  the 
high-pressure  crank  is  on  the  top  or  bottom  center,  a  con- 
dition which  generally  arises  at  the  most  inopportune  times, 
such  as  working  the  vessel  into  a  dock.  However,  by  quickly 
opening  the  pass-over  valve,  a  small  stop  or  slide  valve,  live 
steam  is  admitted  into  the  intermediate  valve  chest,  which 
starts  the  intermediate  piston  in  motion  and  pulls  the  high- 
pressure  crankpin  over  the  center.  The  hand-wheel  or  lever 
for  controlling  the  pass-over  valve  is  always  located  at  the 
working  platform  within  convenient  reach  of  the  man  operat- 
ing the  engine." 

"Why  are  drain  valves  necessary?"  asked  Schmidt. 

"Because  steam  when  entering  a  cold  cylinder  or  valve  chest 
is  condensed  into  water,  which,  if  not  allowed  to  drain  off, 
would  cause  a  water  hammer  and  might  break  a  cylinder 
head.  Drain  valves  are  located  at  the  bottom  of  each  valve 
chest  and  cylinder  at  the  lowest  points.  Sometimes  they  are 
operated  by  means  of  an  extension  rod  and  a  hand-wheel  at 
the  side  of  the  cylinder,  but  more  often  by  means  of  shafts  and 
levers  located  close  up  to  the  working  levers,  so  that  the  man 
operating  the  engine  can  open  or  close  the  dram  from  any 
cylinder  without  leaving  his  position. 

"Relief  valves  are  located  on  each  valve  chest  and  at  the 
top  and  bottom  of  each  cylinder.  These  are,  in  reality,  small 
safety  valves,  similar  to  those  used  on  boilers,  and  are  for 
the  purpose  of  automatically  relieving  any  excess  pressure, 
either  of  steam  or  water,  mostly  that  caused  by  water,  in  the 
cylinders." 

"What  is  the  use  of  a  turning  engine  ?"  inquired  Nelson. 


QO  MC  ANDREW  S    FLOATING   SCHOOL 

"That's  easy,"  volunteered  O'Rourke.  "It's  to  keep  us 
horny-handed  sons  of  toil  out  in  the  fire-room  from  breaking 
our  backs  by  jacking  the  old  engine  over  every  day!" 

"Judging  from  some  firemen  I  have  had  with  me,"  replied 
McAndrew,  looking  straight  at  O'Rourke,  "working  the  turn- 
ing gear  is  about  the  only  real  work  you  can  get  out  of  them 
while  the  vessel  is  in  port. 

"Turning-engines  are  not  usually  fitted  on  engines  of  less 
than  3,000  horsepower,  as  it  is  much  simpler  to  have  the 
ordinary  hand  gear,  which  usually  consists  of  a  large  worm- 
wheel  secured  to  the  crankshaft  just  aft  of  the  engine  bed- 
plate ;  a  small,  vertical  or  inclined  shaft  pivoted  at  the  bottom 
works  the  worm,  which  meshes  with  the  main  turning  wheel, 
the  shaft  being  operated  by  a  ratchet  lever.  If  steam  power  is 
used  it  is  usual  to  drive  the  worm-wheel  by  means  of  one  or 
two  small  cylinders,  the  whole  apparatus  being  so  geared  that 
it  takes  hundreds  of  revolutions  of  the  small  engine  to  turn 
the  main  engine  over  once." 

"Why  do  you  have  to  turn  the  main  engine  over  when  steam 
is  not  on  it?"  asked  Pierce. 

"It  is  quite  often  necessary  to  do  so  when  making  adjust- 
ments to  the  crankpin  brasses,  in  order  to  get  the  particular 
crank  on  the  top  center;  sometimes  it  is  necessary  to  jack  the 
main  engine  over  while  adjusting  the  valve  gear.  All  engines 
in  which  metallic  packing  is  used  for  the  rods  should  be 
jacked  at  least  once  each  day,  in  order  to  prevent  rough  places 
being  formed  on  the  polished  rods  from  standing  too  long  in 
contact  with  the  packing  at  any  particular  point  of  the  stroke. 

"Leaving  the  main  engine  and  looking  aft,  the  first  thing  of 
importance  we  see  is  what  is  known  as  the  'thrust  bearing,' 
a  most  important  element  in  steam  machinery,  as  it  is  by 
means  of  this  piece  of  mechanism  that  all  of  the  driving  power 
of  the  propeller  is  transmitted  to  the  ship  itself. 

"As  the  propeller  revolves  in  the  water  it  has  the  same  ten- 


ENGINE  FITTINGS  QI 

dency  to  advance  that  a  screw  has  in  a  piece  of  wood,  and 
it  is  this  pushing  effect,  or  thrust,  as  it  is  called,  which,  trans- 
'  mitted  through  the  agency  of  the  shafting  and  the  thrust  bear- 
ing, drives  the  ship  along.  This  bearing  therefore  must  be 
firmly  secured  to  the  hull  of  the  ship,  and  must  be  so  designed 
as  not  to  become  overheated  on  account  of  the  necessarily 
large  amount  of  friction  on  the  bearing  surfaces.  That  part 
of  the  shafting  upon  which  the  thrust  bearing  is  located  is 
known  as  the  'thrust  shaft,'  and  it  is  usually  made  short  in 
length  in  order  to  facilitate  its  removal  from  the  ship  when 
it  becomes  necessary,  as  may  happen,  that  it  has  to  be  placed 
in  a  lathe  for  the  purpose  of  removing  the  scores  from  the 
bearing  surfaces.  On  this  thrust  shaft  are  a  number  of  solid 
rings  or  collars,  which  fit  between  what  are  known  as  'horse- 
shoe collars,'  and  which  are  supported  on  rods  on  each  side  of 
the  bearing,  each  being  provided  with  two  adjusting  nuts  on 
the  rods,  so  that  each  individual  horseshoe  may  be  adjusted 
to  bear  a  proportionate  amount  of  the  thrust  of  the  shaft.  The 
bearing  faces  of  these  collars  are  lined  with  white  metal,  so 
as  to  reduce  the  friction  to  a  minimum.  The  bottom  of  the 
bearing  usually  forms  a  rectangular  tank  or  trough,  which  is 
filled  with  oil  so  that  the  collars  on  the  shaft  revolve  in  it  and 
carry  the  lubricant  to  the  bearing  surfaces.  To  keep  the  bear- 
ing cool  it  is  customary  to  fit  a  flat  coil  of  pipe  in  the  bottom 
of  the  oil  reservoir,  and  to  connect  this  coil  to  the  water 
circulating  system.  The  best  thrusts  also  have  separate  water 
pipe  connections  to  each  horseshoe  collar.  Too  much  atten- 
tion cannot  be  given  to  the  thrust  bearing,  for  if  it  is  not 
properly  oiled  and  cooled  a  great  deal  of  trouble  can  arise  on 
account  of  excessive  heating. 

"Just  aft  of  the  thrust  shaft,  the  main  or  'line  shafting'  ex- 
tends to  what  is  known  as  the  'tail  shaft,'  the  last  portion  of 
the  propeller  shafting.  This  line  shafting  is  known  as  the 
intermediate  shaft,  and  is  made  in  one,  two  or  three  sections, 


92  MC  ANDREW'S    FLOATING    SCHOOL 

according  to  the  length  of  the  vessel.  All  lengfhs  of  the  shaft- 
ing proper  are  made  of  the  best  quality  of  wrought  steel,  and 
they  should  be  carefully  forged  and  inspected,  as  the  breaking 
of  any  part  of  this  important  connection  between  the  main 
engine  and  the  propeller  totally  cripples  the  ship  if  she  is  of 
the  single-screw  type.  It  is  customary  to  connect  the  several 


FIG.     19. DETAIL    OF    FLANGE    COUPLING    AND     BOLT 

sections  of  the  shafting  together  by  means  of  what  are  known 
as  flanged  couplings  and  tapered  bolts,  as  shown  in  Fig.  19. 

"The  bolts  are  made  tapered  for  convenience  in  backing 
them  out  whenever  it  becomes  necessary  to  remove  a  section 
of  the  shaft. 

"Each  section  of  the  intermediate  shafting  is  usually  sup- 
ported on  two  bearings,  which  rest  on  suitable  foundations  of 
plates  and  angles  built  up  from  the  frames  of  the  ship.  These 
bearings  probably  have  more  names  than  any  other  part  of 
the  steam  machinery.  Different  people  refer  to  them  as 
'spring  bearings/  'pillow  blocks,'  'tunnel  bearings/  'steady 
bearings'  and  plain  bearings.  However,  no  matter  what  they 
are  called  their  function  is  a  very  simple  one,  namely,  that  of 
supporting  the  weight  of  the  shaft  and  keeping  it  in  aline- 
ment.  With  such  simple  duties  to  perform,  it  is  customary 
to  fit  the  bottom  with  a  brass,  or  to  line  it  with  white  metal. 


ENGINE  FITTINGS  93 

The  top  of  the  bearing  serves  no  other  purpose  than  to  keep 
the  dirt  out  of  it,  and  to  support  oil  cups  or  compression  cups 
containing  grease  for  lubricating  purposes. 

"Inexperienced  oilers,  like  O'Rourke  will  probably  be,  pay  a 
great  deal  of  'attention  to  spring  bearings,  but  the  old  timers 
give  them  a  familiar  slap  in  passing,  as  they  know  that  bear- 
ings of  this  kind  seldom  give  trouble  from  overheating. 

"In  single-screw  vessels  the  tail  shaft,  or  propeller  shaft, 
passes  through  what  is  known  as  the  'stern  tube,'  a  heavy 
cylindrical  iron  or  steel  casting  extending  from  the  after  bulk- 
head of  the  shaft  alley  to  the  eye  of  the  stern  post.  It  is  ad- 
visable, and  also  customary,  to  increase  the  diameter  of  the 
tail  shaft  over  that  of  the  intermediate  shafting,  as  where  it 
passes  through  the  stern  bearing  it  is  not  possible  to  inspect 
it  often,  and  being  constantly  immersed  in  salt  water  it  may 
become  badly  corroded.  To  provide  against  this  corrosion  the 
tail  shaft  is  usually  encased  in  composition  sleeves  shrunk  on 
the  shaft  by  heating  the  casing  before  it  is  slipped  in  place. 
By  carefully  soldering  the  ends  and  the  joints  between  the 
sections  of  the  casing,  the  water  is  usually  kept  out,  but 
unless  the  soldering  is  well  done  the  water  is  liable  to  leak  in 
and  cause  havoc  to  the  shaft. 

"At  the  forward  and  after  ends  of  the  stern  tube,  bearings 
are  formed  of  composition  castings  containing  dovetailed 
grooves.  In  these  grooves  are  strips  of  lignum-vitae,  a  tropical 
wood  and  about  the  hardest  that  grows.  The  bearing  surface 
should  be  on  the  end  of  the  grain,  and  the  strips  should  be  well 
soaked  in  oil  before  being  driven  into  place,  as  the  water 
which  circulates  around  the  shaft  is  the  only  lubricant  it  re- 
ceives. At  the  inboard  end  of  the  stern  tube  there  is  a 
stuffing-box  packed  with  square  hemp  or  flax  packing,  a  job 
which  can  only  be  attended  to  while  the  vessel  is  in  the  dry 
dock.  There  is  usually  fitted  a  small  cock  and  a  pipe  leading 
to  the  water  space,  by  means  of  which  a  small  stream  of  water 


94 


MC  ANDREW'S  FLOATING  SCHOOL 


is  allowed  to  trickle  on  the 
stuffing-box  and  its  gland  in 
order  to  keep  them  cool.  This 
also  allows  a  circulation  of  the 
water  in  the  stern  tube. 

"In  sandy  or  muddy  water 
the  lignum-vitae  in  the  bearings 
is  found  to  cut  out  quickly, 
and  in  some  vessels  it  is  cus- 
tomary to  fit  a  stuffing-box  at 
the  after  end  of  the  after 
bearing  and  to  line  the  stern 
bearing  with  white  metal.  Lub- 
rication is  furnished  to  such  a 
bearing  by  means  of  an  oil  cup 
or  compression  grease  cup 
located  above  the  waterline  in 
an  accessible  position. 

''Fig.  20  will  show  the  usual 
form  of  stern  tube,  bearings, 
etc.,  used  on  single-screw  ves- 
sels." 

"  C  h  i  e  f ,"  interrupted 
O'Rourke,  "you  can't  go  much 
further  aft  without  telling  us 
about  propellers,  can  you?" 

"For  once,  O'Rourke,  you 
are  right,  as  that  is  certainly 
the  next  step. 

"The  subject  of  propellers  is 
one  of  the  most  interesting 
connected  with  marine  engi- 
neering. Volumes  have  been 
written  about  them,  and  nearly 


ENGINE  FITTINGS  gcj 

every  engineer  of  any  standing  in  the  business  has,  at  one 
time  or  another  in  his  career,  attempted  to  invent  a  new  kind 
that  would  be  far  superior  to  any  other  propeller  ever  made. 
The  Patent  Office  contains  about  as  many  propeller  designs 
as  there  are  ships  on  the  seas.  About  one  of  these  designs  in 
ten  thousand  is  of  any  practical  use,  so  let  me  warn  you  young 
men  never  to  let  your  fancies  run  to  the  idea  that  you  can 
invent  a  propeller. 

'The  whole  science  of  propeller  designing  is  based  on  a 
process  of  evolution.  Do  you  know  what  'evolution'  means, 
O'Rourke?" 

''Sure !"  said  he  of  Irish  extraction.  "That  means  that  man 
is  descended  from  a  monkey." 

"You  have  the  idea  all  right,  and  the  modern  propeller  has 
about  the  same  relation  to  the  original  propeller  as  a  man 
bears  to  his  original,  in  accordance  to  the  theory  of  a  certain 
philosopher  named  Darwin. 

"When  propellers  were  first  invented,  the  idea  was  that 
they  should  be  as  large  as  it  was  possible  to  have  them.  A 
story  is  told  of  an  old-time  coasting  steamer  fitted  with  an 
engine  of  five  or  six  hundred  horsepower  driving  a  four- 
bladed  propeller  about  15  feet  in  diameter.  She  was  ambling 
up  the  coast  one  day  at  a  6-knot  clip  when  the  propeller 
struck  a  log;  whereafter,  as  the  story  goes,  she  imme- 
diately increased  her  speed  to  7  knots.  On  examination  it  was 
found  that  one  of  the  blades  had  been  broken  off,  a  fact  which 
immediately  started  the  theory  that  a  three-bladed  propeller 
was  the  proper  thing  to  use.  As  a  matter  of  fact,  the  in- 
creased speed  was  undoubtedly  due  to  the  reduction  in  area  of 
an  excessively  large  propeller. 

"The  best  designed  propellers  of  to-day  are  those  built  in 
accordance  with  data  derived  from  propellers  which  have  been 
in  use.  Step  by  step  they  have  been  improved  upon  until  ft  seems 
that  we  have  to-day  reached  a  point  where  but  little  more 


96  MC  ANDREW'S  FLOATING  SCHOOL 

improvement  can  be  made.  The  crude  propellers  used  on  the 
first  screw  steamers  and  all  propellers  used  since  that  time 
have  been  useful  in  developing  the  modern  propeller,  as  it  has 
been  from  actual  experience,  and  after  very  expensive  ex- 
perience, too,  that  perfection  in  propeller  design  has  been 
gradually  approached. 

"The  results  of  all  these  years  of  experimenting  have 
evolved  a  standard  wheel  with  uniform  pitch  and  blades 
elliptical  in  shape  set  at  right  angles  to  the  shaft  axis,  or 
slightly  raked  aft  from  the  perpendicular,  according  to  the 
individual  fancy.  The  great  majority  of  propellers  are  now 
four-bladed,  a  small  portion  of  them  three-bladed,  and  oc- 
casionally we  see  a  two-bladed  propeller  on  an  auxiliary 
vessel. 

"Propellers,  small  in  diameter,  are  almost  invariably  made 
solid ;  that  is,  the  hub  and  blades  are  cast  in  one  piece,  such 
as  shown  in  Fig.  21. 

"Larger  propellers  are  of  the  'built-up'  type;  that  is,  the 
blades  and  hub  are  cast  separately  and  the  blades  are  flanged 
and  bolted  to  the  hub.  The  advantages  of  this  type  are  that 
in  case  any  of  the  blades  are  broken  they  can  be  replaced 
without  throwing  away  the  entire  wheel,  and,  further,  that 
by  slotting  the  holes  in  the  blade  flanges  the  pitch  can  be 
altered  if  deemed  necessary." 

"What  material  is  best  for  propellers?"  inquired  Nelson. 

<rThat  depends  on  how  much  money  you  have,"  replied  the 
chief.  "In  fact  it  is  something  like  buying  underclothes.  A 
poor  man  buys  cotton  and  it  serves  the  purpose ;  a  man  of 
moderate  means  buys  woolen — that  serves  the  purpose  better ; 
a  rich  man  would  buy  silk,  and  that  is  better  than  any  of  the 
others. 

"With  propellers,  cast  iron  serves  the  purpose  and  is  cheap ; 
~ast  steel  is  stronger  and  costs  a  little  more ;  bronze  is 


ENGINE  FITTINGS 


97 


98  MC  ANDREW'S  FLOATING  SCHOOL 

stronger,  smoother  and  lasts  longer,  but  costs  much  more  than 
either  of  the  other  materials." 

"I  think  Schmidt  must  wear  a  cast  iron  undershirt,  judging 
from  the  rust  he  has  on  it,"  suggested  O'Rourke. 

"If  shipowners  but  knew  it,  polished  manganese  bronze  or 
other  high-class  materials  would  be  much  cheaper  in  the  end 
than  cast  iron  or  cast  steel.  A  screw  driven  into  wood  en- 
counters considerable  friction,  and  you  will  be  surprised  to 
learn  that  the  screw-propeller  driven  through  the  water  also 
encounters  a  great  deal  of  friction.  Experiments  have  shown 
that  from  10  to  20  percent  of  the  total  power  of  the  engine 
is  consumed  in  overcoming  the  friction  of  the  screw.  Hence 
it  pays  to  have  the  blades  made  as  smooth  as  possible  to 
reduce  this  frictional  loss.  Recent  experiments  of  rubbing 
graphite  on  the  blade  surfaces  demonstrate  that  an  appreciable 
amount  of  friction  is  reduced  by  means  of  that  lubricant." 

"What  do  they  mean  by  the  pitch  of  a  propeller?"  asked 
Pierce. 

"McAndrew  picked  up  a  bolt  that  was  lying  on  a  bench,  and 
said:  "I  hold  this  nut  rigid  in  my  hand  and  turn  the  bolt 
head  one  complete  revolution ;  you  will  see  that  the  end  of  the 
bolt  has  advanced  about  1/16  inch  out  of  the  nut — that  is 
what  is  called  the  'pitch'  of  the  thread  on  the  bolt.  So  with 
propellers,  the  pitch  is  the  distance  the  ship  should  be  driven 
ahead  by  one  revolution  of  the  screw  if  it  was  driven  through 
a  solid.  But  water  is  not  solid  by  any  means,  and  hence  the 
ship  does  not  advance  the  distance  it  should;  the  difference 
between  what  it  does  advance  and  what  it  would  advance  in  a 
solid  is  called  the  'slip.'  This  term  is  always  expressed  in 
percentage;  for  example,  if  the  pitch  of  the  screw  is  20  feet, 
and  the  ship  is  driven  ahead  only  17  feet  at  one  revolution  of 
the  engine,  the  slip  is  3  feet,  and  there  would  be  said  to.be  a 
15  percent  slip,  as  3  is  15  percent  of  20." 


ENGINE  FITTINGS  99 

"How  do  you  tell  whether  a  propeller  is  right  or  left- 
handed?"  asked  Schmidt. 

"The  best  way  to  tell  that  is  to  imagine  yourself  in  the 
bottom  of  the  dry  dock  looking  forward  at  the  propeller. 
When  the  screw  is  driving  the  ship  ahead  and  it  turns  in  a 
direction  corresponding  to  the  motion  of  the  hands  of  a  watch 
it  is  called  right-handed.  If  in  the  opposite  direction  then  it 
is  left-handed. 

"The  driving  face  of  a  blade  is  not,  as  you  might  imagine, 
the  forward  side,  but  the  after  side,  as  it  is  that  side  which 
acts  on  the  water ;  therefore  the  back  of  a  blade  is  its  for- 
ward side." 

"That  sounds  Irish,"  said  Schmidt,  glancing  at  O'Rourke. 

"The  area  of  a  propeller,  sometimes  called  the  helicoidal 
area,  is  the  sum  of  the  actual  areas  of  all  of  its  blades. 

"Later  on  I  will  try  to  show  you  how  to  calculate  the  pitch 
of  a  propeller  by  measuring  the  wheel  in  position." 


CHAPTER   XII 

Condensers,  Air  and  Circulating  Pumps 

The  repairs  to  the  Tuscarora  were  rapidly  nearing  com- 
pletion ;  the  new  boilers  were  in  place,  much  of  the  connecting 
piping  had  been  gotten  out  and  the  end  of  the  job  was  in  sight. 
The  students  of  the  "Floating  School"  had  not  lost  interest  in 
their  voluntary  work,  although  their  regular  duties  were  now 
much  harder  than  at  the  commencement  of  the  repairs. 
McAndrew  had  looked  for  his  pupils  to  slacken  in  their  in- 
terest in  his  lectures,  but  no  one  had  missed  a  single  evening 
which  he  had  devoted  to  their  instruction.  In  consequence  he 
had  determined  to  carry  the  course  through  for  them,  and 
on  this  particular  evening  in  early  March  he  opened  his  re- 
marks by  saying : 

"Well,  boys,  this  work  I  know  is  rather  dry  to  you,  but  later 
on  we  will  get  into  something  more  interesting  to  you.  I 
propose  to  cover  all  the  principal  parts  of  marine  machinery  by 
these  lectures,  and  then  to  give  you  some  practical  questions 
on  the  subject  and  to  show  you  how  various  problems  are 
worked  out. 

"Up  to  date  I  have  tried  to  instruct  you  in  a  general  way 
as  to  how  steam  is  generated  and  how  it  is  utilized  to  pro- 
duce power.  We  now  come  to  the  part  where,  having  used 
the  steam,  we  must  get  rid  of  it.  This  is  a  step  second  only 
in  importance  to  generating  the  steam.  We  have  seen  that  by 
applying  heat  to  water  in  the  boiler  steam  is  formed ;  the  con- 
denser serves  directly  the  opposite  purpose,  for  therein  the  heat 
is  taken  out  of  the  steam  and  it  returns  to  its  original  state — 
water.  Some  people  look  at  the  condensers  as  if  there  were 


CONDENSERS,   AIR  AND   CIRCULATING   PUMPS  101 

something  mystifying  about  its  action,  but  the  process  of  con- 
densation is  simplicity  itself.  The  very  atmosphere  we  breathe 
acts  as  a  condenser,  for  you  no  doubt  have  noticed  how  readily 
steam  escaping  from  an  exhaust  pipe  is  turned  into  water 
simply  by  contact  with  the  air,  and  especially  is  this  noticeable 
on  a  cold  day. 

"You  might  think  that  in  the  steam  as  it  leaves  the  engine 
there  is  but  little  heat  left,  and  as  a  matter  of  fact  the  tem- 
perature is  only  about  no  degrees  F. ;  but  you  must  remember 
the  first  principles  and  realize  that  the  temperature  as  shown 
by  the  thermometer  is  only  the  sensible  heat.  Do  not  forget 
that  when  the  water  was  transformed  into  steam  it  took  about 
934  heat  units,  known  as  the  latent  heat,  to  bring  about  this 
change  of  state.  To  turn  the  steam  into  water  again  this  latent 
heat  must  be  taken  out  in  order  to  accomplish  the  change, 
and,  approximately  speaking,  there  are  1,000  heat  units  per 
pound  of  steam  to  be  carried  off  by  the  cooling  water.  Herein 
lies  one  of  the  great  wastes  of  any  steam  plant,  and  unless  the 
exhaust  steam  can  be  utilized  for  heating  the  feed  water,  or 
for  heating  buildings  in  the  case  of  shore  plants,  there  is  no 
way  yet  devised  to  prevent  it." 

"Chief,"  interrupted  Pierce,  "I  don't  understand  how  this 
exhaust  steam  can  have  so  low  a  temperature  as  no  degrees 
F.,  when  you  told  us  that  steam  did  not  form  until  the  ther- 
mometer stood  at  212  degrees  F." 

"I  see,"  replied  the  instructor,  "that  you  did  not  grasp  the 
idea  of  water  boiling  at  different  temperatures  according  to 
the  pressure  it  is  under.  It  is  true  that  under  atmospheric 
pressure  it  does  not  form  steam  until  212  degrees,  but  as  the 
pressure  is  reduced  the  boiling  point  is  lowered  accordingly. 
Steam  leaving  the  low-pressure  cylinder  of  an  engine  is  at  an 
absolute  pressure  of  only  a  pound  or  two  corresponding  to  a 
vacuum  of  26  or  27  inches,  and  if  you  were  to  boil  water  in 
such  a  vacuum  you  would  find  that  steam  forms  at  a  tern-, 


IO2  MC  ANDREW'S  FLOATING  SCHOOL 

perature  of  approximately  no  degrees.  Hence  it  is  that  the 
exhaust  steam  has  such  a  low  temperature. 

"Fortunately  the  best  medium  for  condensing  steam  is  cool 
water,  so  on  shipboard  the  supply  of  cooling  water  is,  of 
course,  close  at  hand.  The  condenser,  as  the  apparatus  for 
bringing  about  the  transformation  from  steam  to  water  is 
termed,  is  made  in  two  principal  types  for  marine  purposes. 
The  jet  condenser  consists  of  a  large  cylindrical  casting  into 
which  the  exhaust  steam  passes,  and  where  it  comes  in  contact 
with  jets  of  water  which  transform  or  condense  the  steam 
to  water.  As  the  condensing  water  is  used  in  such  large 
quantities  it  must  be  pumped  overboard,  together  with  the 
water  of  condensation.  For  vessels  sailing  on  fresh  water  such 
a  device  is  cheap,  economical  and  highly  efficient,  but  for 
vessels  plying  in  salt  water  where  the  condensed  exhaust  steam 
must  be  used  over  and  over  again  for  boiler  feed,  jet  con- 
densation is  absolutely  useless.  Hence  we  have  what  is  known 
as  the  surface  condenser,  wherein  the  steam  does  not  come  in 
direct  contact  with  the  circulating  or  cooling  water. 

"Surface  condensers  are  made  either  cylindrical  or  rec- 
tangular in  section,  according  to  the  space  which  they  are  to 
occupy.  When  they  are  built  in  the  engine  framing,  as  most 
frequently  happens  in  merchant  vessels,  they  usually  have  a 
cylindrical  top  with  flat  sides  and  bottom,  strongly  ribbed 
to  prevent  collapse  from  the  external  pressure  of  the  atmos- 
phere. At  each  end  of  the  condenser  there  is  what  is  known 
as  a  water  chest  for  the  entrance  and  exit  of  the  circulating 
water.  The  greater  portion  of  the  interior  of  the  condenser  is 
filled  with  small  brass  tubes,  usually  5/£  inch  outside  diameter, 
running  lengthwise,  and  fitting  into  what  are  known  as  tube 
sheets,  one  at  each  end  of  the  condenser.  These  tubes  are 
spaced  very  closely  together,  and  through  them  flows  the  cool 
sea  water.  The  exhaust  steam  as  it  enters  the  condenser  thus 
comes  in  direct  contact  with  the  outer  surface  of  these  small 


CONDENSERS,    AIR   AND    CIRCULATING    PUMPS 


103 


tubes  and  is  quite  readily  transformed  into  water.  In  order  to 
prevent  the  steam  from  striking  the  tubes  in  one  spot  directly 
opposite  the  exhaust  pipe,  it  is  customary  to  fit  a  perforated 
baffle  plate  opposite  the  opening  for  the  exhaust,  which  baffle 
plate  scatters  or  deflects  the  steam  along  the  entire  length  of 
the  tubes.  It  is,  of  course,  highly  essential  that  the  condenser 


FIG.    22. FERRULES   AND    TUBE    PACKING    IN    SURFACE   CONDENSER 


be  kept  as  tight  as  possible,  for  if  there  are  any  leaks  the  salt 
circulating  water  will  be  forced  into  the  body  of  the  con- 
denser, where  it  will  mix  in  with  the  condensed  steam  and  find 
its  way  into  the  boilers.  Hence  great  care  must  be  exercised 
in  packing  the  ends  of  the  innumerable  small  tubes.  Fig.  22. 
will  show  you  how  these  tube  ends  are  made  tight. 

"Holes  are  tapped  in  the  tube  sheets  into  which  are  screwed 
small  glands  known  as  ferrules,  and  the  packing  space  is 
usually  filled  with  corset  lacing." 


104  MC  ANDREW'S  FLOATING  SCHOOL 

"Gee!"  exclaimed  O'Rourke,  "they  ought  to  carry  lots  of 
girls  on  ships  to  furnish  all  that  corset  lacing." 

"You  will  notice,"  continued  McAndrew,  "that  the  ends  of 
these  glands  or  ferrules  are  beaded  over  slightly.  That  serves 
the  purpose  of  preventing  the  tubes  from  crawling  out  of  place 
on  account  of  the  contraction  and  expansion  due  to  the  varying 
temperatures  to  which  these  long,  slender  metal  tubes  are  sub- 
jected. It  also  allows  them  to  expand  without  starting  to  leak, 
as  would  otherwise  be  the  case. 

"If  condenser  shells  are  cylindrical  in  shape  it  is  usual  to 
make  them  from  rolled  steel  plate,  but  if  they  are  of  rec- 
tangular section  they  are  almost  invariably  made  of  cast  iron. 
The  tube  sheets  are  always  made  of  composition.  The  tubes 
themselves  are  made  either  of  brass  or  Muntz  metal,  usually 
coated  outside  and  inside  with  tin,  although  many  designers 
do  not  think  that  this  tinning  process  is  now  necessary.  At  the 
water  ends,  particularly,  where  iron  and  brass  are  in  such  close 
proximity,  it  is  very  important  to  see  that  a  sufficient  amount 
of  zinc  plates  is  suspended  in  the  water  to  prevent  galvanic 
action.  Some  careful  engineers  also  have  zinc  plates  fitted  in 
baskets  in  the  fresh-water  side  of  the  condenser  for  the  same 
purpose,  although  these  are  not  so  essential  there  as  in  the 
water  chests. 

"This  evening  as  I  was  coming  into  the  engine  room  I 
noticed  you  boys  looking  around  the  main  condenser,  so  I  sup- 
posed you  were  trying  to  study  its  connections." 

"Yes,"  replied  O'Rourke,  "Schmidt  was  trying  to  find  how 
the  air  got  into  the  air  pump  when  there  is  only  steam  goes 
into  the  condenser." 

"I  suppose,"  replied  McAndrew,  "that  the  air  gets  in  the 
air  pump  just  about  the  same  way  that  water  gets  in  the  milk 
we  buy  at  the  corner  grocery — it's  put  in.  The  term  'air  pump' 
is  really  a  misnomer;  to  be  sure,  there  is  a  small  amount  of 
air  gets  into  the  condenser  with  the  steam,  but  the  main  func- 


CONDENSERS,    AIR   AND   CIRCULATING   PUMPS  IO5 

tion  of  an  air  pump  is  to  pump  the  condenser  water  out  of  the 
condenser,  and  incidentally  any  air  and  vapor  that  may  be 
there. 

"Air  pumps  on  board  ships  are,  as  a  rule,  vertical,  and  of 
two  general  types,  connected  and  independent.  By  'connected' 
we  mean  that  they  are  worked  through  the  medium  of  beams 
from  one  of  the  crossheads  of  the  main  engine,  usually  the 
low  pressure.  The  principal  advantages  of  this  arrangement 
are  the  certainty  of  action  so  long  as  the  engine  is  running 
and  the  economy  of  operation,  as  the  power  is,  of  course,  fur- 
nished by  the  main  engine,  which  is  generally  of  the  most 
economical  multiple-expansion  type.  Its  disadvantage  is  that 
there  is  no  vacuum  while  the  main  engine  is  not  running. 
This,  however,  is  not  great,  as  the  vacuum  is  produced  almost 
at  the  first  stroke  of  the  main  engine. 

"An  'independent'  air  pump  is  one  that  is  driven  by  its  own 
steam  cylinders ;  and  as  a  rule  .this  type  is  uneconomical,  as 
the  economy  of  operation  is  only  equivalent  to  that  of  a  slow- 
running  simple  engine.  There  is  an  advantage,  of  course,  in 
always  having  a  vacuum  in  the  condenser  whether  the  main 
engine  is  running  or  not.  Unless  an  independent  air  pump 
is  of  very  good  design  and  kept  in  good  order,  there  is  always 
a  likelihood  of  its  stopping  at  the  most  inopportune  times.  In 
this  they  closely  resemble  a  mule  who  will  work  along  all  right 
•until,  perhaps,  when  crossing  a  railroad  track,  he  will  get 
balky  just  as  a  train  is  coming  along." 

''Do  you  start  a  balky  pump  the  same  way  that  you  would 
start  the  mule?"  inquired  Pierce. 

"Very  much  the  same,"  replied  McAndrew.  "I  once  had  an 
Irish  oiler  with  me  who  would  occasionally  get  mad  when  the 
air  pump  stopped,  and  would  strike  it  on  the  valve  chest  with 
a  top-maul.  Very  frequently  the  pump  would  start  off  im- 
mediately on  being  -given  that  treatment,  probably  because  the 
jar  would  start  the  controlling  valve  which  had  stuck.  How- 


io6  MC  ANDREW'S  FLOATING  SCHOOL 

ever,  I  do  not  recommend  such  strenuous  treatment  of  balky 
pumps,  and  you  had  better  not  let  me  catch  any  of  you  striking 
pump  valves  that  way  on  board  this  ship. 

"The  air  pump  itself  is  usually  of  the  same  design,  whether 
operated  independently  or  attached  to  the  main  engine.  Fig. 
23  will  show  you  the  type  usually  adopted  for  marine  work. 

"Air  pumps  are  always  attached  to  the  very  lowest  part  of 
the  condenser,  so  that  the  water  of  condensation  will  flow  to 
the  pump  by  gravity.  In  the  sketch  you  will  note  that  the 
pump  is  not  unlike  any  ordinary  style  of  pump  for  pumping 
liquids.  The  valves  form  the  main  distinguishing  feature. 
There  are,  as  you  will  see,  three  sets  of  these  valves ;  the  ones 
at  the  bottom  being  termed  'foot  valves/  those  in  the  piston  are 
known  as  'bucket  valves/  and  the  set  of  valves  at  the  top  are 
'discharge  valves.' 

"The  method  of  operation  is  that  as  the  bucket  or  piston 
starts  on  its  upward  stroke  a  vacuum  is  produced  in  the 
pump  barrel,  which,  when  it  overcomes  the  vacuum  in  the  con- 
denser, causes  the  water,  air  and  vapor  to  rush  through  the 
foot  valves  into  the  body  of  the  pump.  On  the  down  stroke 
the  contents  of  the  pump  are  in  turn  discharged  through  the 
bucket  valves,  and  on  the  following  up-stroke  are  forced 
through  the  discharge  valves  at  the  top,  whence  they  go  to  the 
hot  well  or  feed  tank.  You  will  notice  that  the  top  plate  on  the 
pump  which  contains  the  discharge  valves  is  not  bolted  to  the 
pump  in  this  sketch,  but  is  held  down  by  a  large  spiral  spring. 
This  is  what  is  known  as  a  floating  top,  and  it  is  thus  ar- 
ranged so  as  to  allow  the  ready  escape  of  a  large  volume  or 
gulp  of  water  which  is  liable  to  pass  through  the  pump  at  any 
time.  Quite  often  pumps  which  have  not  been  provided  with 
bucket  on  a  large  mass  of  water  which  could  not  escape  quickly 
a  floating  top  have  had  the  top  broken  by  the  impact  of  the 
enough  through  the  small  valves.  Most  large  air  pumps  are 


CONDENSERS,    AIR   AND    CIRCULATING    PUMPS 


FIG.    23. — VERTICAL   ATTACHED    AIR    PUMP 


IO8  MC  ANDREW'S  FLOATING  SCHOOL 

made  of  cast  iron,  fitted  with  a  thin  composition  liner.  The 
bucket  should  be  of  composition,  and  the  top  and  bottom  valve 
plates  should  also  be  made  of  the  same  material. 

"The  air  pump  valves  nowadays  are  usually  made  of  several 
light  bronze  disks  of  decreasing  diameters,  the  largest  diameter 
being  at  the  bottom.  These  are  held  down  by  light  bronze 
wire  spiral  springs.  Some  engineers,  however,  still  prefer 
vulcanized  rubber  valves. 

"You  will  notice  that  the  bucket  shown  in  this  sketch  has  a 
number  of  grooves  turned  in  its  rim;  these  are  supposed  to 
trap  small  quantities  of  water  and  thus  prevent  leakage  from 
one  side  to  the  other.  Ordinarily  buckets  of  this  kind  are  fitted 
with  bull  rings  and  packed  with  square  hemp  packing,  as  that 
is  much  more  reliable  than  the  so-called  water  packing. 

'Tumps  above  18  or  20  inches  in  diameter  are  usually  fitted 
with  a  manhole  in  the  side  of  the  barrel,  so  as  to  provide 
ready  access  to  the  bucket  and  foot  valves  without  removing 
the  top  and  the  bucket  as  well  whenever  it  is  necessary  to  ex- 
amine the  lower  sets  of  valves. 

"What  pump  on  board  of  a  ship  do  you  think  has  the  easiest 
job?"  inquired  McAndrew,  trying  to  test  the  knowledge  of  his 
pupils. 

"I  know,"  quickly  said  O'Rourke,  "it's  the  pump  in  the  fire- 
men's washroom  when  Schmidt  is  taking  a  bath — he's  afraid 
of  water." 

"I  haven't  heard  of  any  pump  handles  being  broken  when 
you  were  taking  a  bath,  either,"  retorted  Schmidt. 

"Well,  you  will  have  to  decide  the  bathing  proposition  your- 
selves," remarked  McAndrew.  "But  what  I  wanted  to  call  to 
your  attention  is  the  fact  that  the  circulating  pump,  a  very 
important  adjunct  of  marine  machinery,  has  comparatively 
little  hard  work  to  do.  In  condensing  the  exhaust  steam  a 
very  large  quantity  of  circulating  water  is  used,  as  for  every 
pound  of  steam  condensed  there  is  required  under  ordinary 


CONDENSERS,   AIR  AND   CIRCULATING   PUMPS  lOp 

conditions  the  cooling  effect  of  about  30  pounds  of  sea  water. 
Thus  for  a  4,ooo-horsepower  engine,  using  about  16  pounds  of 
steam  per  horsepower  each  hour,  there  would  be  required 
about  3,800  gallons  of  circulating  water  per  minute.  This 
water  has,  however,  only  to  be  pumped  with  sufficient  force 
to  overcome  the  friction  through  the  tubes  and  the  small  head 
due  to  forcing  it  overboard  a  few  feet  above  the  pump.  The 
requisite  force  is  so  small  that  on  fast  torpedo  boats  there 
is  a  scoop  arrangement  at  the  in-take  which,  when  the  vessel 
is  going  at  full  speed,  is  sufficient  to  drive  the  circulating  water 
through  the  condenser  without  the  help  of  the  pump. 

"The  pump  almost  universally  used  for  circulating  purposes 
is  of  what  is  known  as  the  centrifugal  type — with  the  accent 
on  'trif  and  not  on  the  'fug,'  as  I  have  heard  some  of  you  boys 
pronounce  it.  By  the  way,  does  any  of  you  know  the  meaning 
of  'centrifugal?' " 

Not  even  O'Rourke  ventured  a  reply,  so  McAndrew  in- 
formed his  hearers  that  "  'centrifugal'  means  'flying  from  the 
center,'  the  opposite  effect,  or  'flying  towards  the  center,'  being 
expressed  by  the  word  'centripetal.'  A  pump  of  the  centrifugal 
type  is  therefore  one  in  which  the  water  entering  at  the 
center  is  driven  outward  by  a  revolving  series  of  blades  called 
the  'runner,'  and  is  discharged  through  an  opening  in  the 
casing  which  is  connected  by  a  pipe  to  the  condenser.  This  is 
an  ideal  type  of  pump  for  circulating  the  water  through  the 
condenser,  inasmuch  as  a  large  quantity  of  water  can  readily 
be  handled  at  a  small  expenditure  of  power.  Pumps  of  this 
description  are  ordinarily  operated  by  a  single-cylinder  engine 
of  the  usual  type.  An  extension  of  the  crankshaft  of  the 
engine  forms  the  shafting  for  the  pump  runner,  and  inside  the 
pump  casing  this  shafting  is  usually  encased  in  composition. 
The  runner  is  generally  cast  of  composition,  but  with  the  ex- 
ception of  small  pumps  the  pump  casing  is  made  of  cast  iron, 
in  halves,  flanged  and  bolted  together.  Pumps  of  this  de- 


IIO  MC  ANDREW'S   FLOATING    SCHOOL 

scription  need  but  little  attention,  as  there  are  no  valves  to 
get  out  of  order  as  is  the  case  with  the  ordinary  types  of  re- 
ciprocating pumps.  Being  of  such  an  advantageous  type, 
centrifugal  feed  pumps  are  now  used  on  shipboard  to  a  limited 
extent,  little  difficulty  being  encountered  in  forcing  water  into 
a  boiler  against  a  pressure  of  as  high  as  200  pounds.  Feed 
pumps  of  this  description  are  driven  by  small  steam  turbines." 

''Suppose  the  circulating  pump  should  break  down,  how 
would  you  keep  running?"  inquired  the  observing  Nelson. 

"There  is  very  little  possibility  of  such  an  accident  oc- 
curring, but  it  is  a  wise  thing  to  prepare  for  even  so  remote 
an  emergency,"  answered  McAndrew.  "I  have  seen  some 
ships  fitted  with  a  special  discharge  pipe  from  the  fire  pump 
or  the  auxiliary  feed  pump  to  the  water  end  of  the  condenser. 
I  know  of  one  ship  in  particular  where  the  casing  of  the  cir- 
culating pump  collapsed  on  account  of  excessive  corrosion  on 
the  inside.  The  chief  engineer  was  a  resourceful  fellow,  and 
fitted  two  hose  connections  to  the  small  handhole  plates  on  the 
water  chest  of  the  condenser;  then  by  connecting  up  two 
lengths  of  fire  hose  to  the  fire  main  and  running  the  auxiliary 
feed  pump,  he  managed  to  keep  sufficient  vacuum  in  the  con- 
denser to  run  the  engine  along  at  half  speed,  and  the  ship 
got  safely  into  port." 

"Suppose  your  air  pump  busted,  what  would  you  do?"  asked 
O'Rourke,  not  to  be  outdone  in  asking  questions  by  his  mates. 

"Even  the  permanent  disabling  of  the  air  pump  need  not 
put  the  engine  out  of  business,"  replied  the  Chief.  "If  worse 
came  to  worse,  you  could  take  down  the  main  exhaust  pipe, 
rig  up  a  temporary  pipe  out  of  heavy  canvas,  and  exhaust  to 
the  atmosphere — tugboat  fashion.  Many  steamers  have  a 
suction  pipe  connecting  the  channel-way  under  the  air  pump 
direct  to  the  main  feed  pump.  By  this  method  the  condenser 
can  be  kept  clear  of  water,  and  a  fair  amount  of  vacuum 
maintained. 


CONDENSERS,    AIR  AND   CIRCULATING   PUMPS  III 

"You  will  find,  as  you  live  longer,  that  the  application  of 
good  common  sense  and  some  ingenuity  will  help  you  out  of 
many  difficulties  which  at  first  seem  insurmountable.  These 
attributes  are  possessed  by  almost  every  marine  engineer,  as 
the  very  nature  of  his  business  requires  a  liberal  use  of  both 
of  them.  Those  are  the  qualities  which  make  marine  engineers 
the  best  operating  engineers  for  any  type  of  machinery." 


CHAPTER  XIII 

Feed  Water   Filters,    Pumps    and    Injectors 

"Having  followed  the  steam  along  until  it  is  condensed  into 
water,  our  next  step  will  be  to  get  it  back  into  the  boiler, 
ready  for  its  transformation  into  steam  again ;  incidentally  we 
will  stop  at  one  or  two  of  the  way-stations,  as  they  say  on 
railroads. 

"After  the  water  leaves  the  hot  well  or  the  air  pump,  it  is 
usual  to  subject  it  to  a  filtering  process  in  order  to  remove 
the  grease  and  other  impurities  which  become  mixed  with  the 
steam  as  it  passes  through  the  engine.  Impure  water  is  just 
as  bad  for  boilers  as  it  is  for  human  beings:  while  an  occa- 
sional dose  of  oil  is  said  to  be  good  for  the  human  system, 
it  is  never  good  for  a  boiler's  'system/  hence  every  effort  is 
exerted  to  keep  it  out  of  the  feed  water.  Most^  ships  are  fitted 
with  what  is  known  as  a  filter  tank,  which  serves  the  double 
purpose  of  a  reservoir  for  the  feed  water  and  a  receptacle  for 
filtering  materials. 

"The  filter  tank  is  customarily  fitted  with  a  number  of 
compartments  through  which  the  feed  water  is  drawn  by  the 
action  of  the  feed  pump — usually  going  up  in  one  compart- 
ment and  down  in  the  adjoining  space.  By  this  means  for  a 
distance  of  from  four  to  ten  feet,  according  to  the  size  of 
the  tank,  it  flows  through  the  filtering  material,  and  the  oil 
is  supposed  to  be  caught  thereby.  The  material  most  com- 
monly used  is  'excelsior'  (small  wooden  strings),  because  of 
its  fairly  good  qualities  for  absorbing  or  entrapping  the  grease 
globules  as  well  as  its  very  cheap  cost.  Ordinary  hay  is  some- 


FEED    WATER   FILTERS,    FUMPS    AND    INJECTORS  113 

times  used,  but  it  is  not  as  efficient  as  the  excelsior.  Sponges 
are  used  to  some  extent,  but  they  are  so  expensive  that  they 
cannot  be  thrown  away  after  becoming  oil-soaked,  and  clean- 
ing them  to  be  used  again  is  not  a  job  relished  by  the  oilers  and 
firemen.  A  spongy  vegetable  substance  known  as  'loofa'  is 
occasionally  used,  but  that  too  is  expensive  and  has  to  be 
washed  out  and  replaced  in  the  compartments.  There  are 
several  patented  filters  on  the  market  which  utilize  various 
woven  filtering  materials,  such  as  gunny  sacks,  etc.,  but  they 
are  all  for  the  accomplishment  of  one  object — the  removal  of 
grease  and  oil,  the  only  real,  thorough  cure  for  which  is  to 
refrain  from  its  use  entirely." 

"That,"  interrupted  O'Rourke,  "is  like  curing  a  mad  dog 
by  cutting  off  his  tail  close  up  behind  his  ears." 

"You  have  the  idea  all  right,  but  you  will  find  that  both 
these  remedies  are  difficult  of  accomplishment,"  answered  the 
instructor. 

"Now  as  to  the  feed  tank's  use  as  a  reservoir — it  should 
have  an  ample  capacity  for  at  least  five  minutes'  supply  of 
feed  water  for  the  boilers  when  the  engine  is  running  at  full 
speed,  in  order  to  allow  for  the  fluctuations  between  supply 
and  demand  in  all  steam  plants.  When  feed  pumps  were 
located  in  the  fire  rooms,  water  tenders  would  have  to  run 
back  and  forth  to  see  that  the  water  in  the  tank  was  not  so 
low  that  the  feed  pump  was  pumping  air  into  the  boilers,  or 
else  not  so  high  as  to  be  overflowing  into  the  bilges.  The 
proper  system  is  to  have  the  feed  pumps  located  in  the 
engine  room  as  near  as  practicable  to  the  feed  tank,  then  by 
means  of  a  float,  rising  and  falling  with  the  level  of  the 
water,  and  connected  by  means  of  rods  and  bell  cranks  to  a 
micrometer  valve  in  the  main  feed  pump  steam  line,  the 
system  is  so  regulated  that  the  water  level  in  the  tank  can  be 
automatically  adjusted. 

"We  are  now  up  to  the  subject  of  boiler  feeding,  and  in  this 


IJ4  MC  ANDREW'S  FLOATING  SCHOOL 

connection  I   will  ask  you:  How   does  your  supper  to-night 
compare  in  importance  with  feeding  the  boilers?" 

"We  get  our  feed  and  some  money  besides,  while  as  far  as 
I  can  see  all  a  boiler  gets  is  its  feed,"  said  Pierce. 

"No,  that  isn't  it,"  broke  in  O'Rourke,  "a  boiler  lives  on 
liquid  food  and  has  to  be  fed  all  the  time  it  is  working,  while 
we  have  to  work  all  day  and  only  get  fed  once  "in  a  while — 
and  it's  pretty  bum  stuff  at  that.  Mr.  Boiler,  though,  has  to 
have  his  feed  of  the  purest  brand." 

"That's  true,"  replied  McAndrew,  "but  you  must  remember 
that  the  boiler's  stomach  is  only  of  steel,  while  from  what  I 
hear,  you  have  a  copper-lined  stomach. 

"However,  I  am  glad  that  you  appreciate  the  fact  that  a 
boiler  has  to  be  fed  continually  while  it  is  working,  as  that 
is  the  most  important  thing  an  engineer  has  to  contend  with. 
If  anything  goes  wrong  with  the  main  feed  pump  there  is  the 
dickens  to  pay,  as  the  boiler's  appetite  for  water  allows  of  no 
delay. 

"On  most  ships  there  are  at  least  three  means  of  forcing  in 
the  feed  water — the  main  feed  pump,  the  auxiliary  feed  pump 
and  the  injector.  It  would  be  a  rare  series  of  accidents,  in- 
deed, when  at  least  one  of  these  contrivances  would  not  be 
available  for  feeding  purposes. 

"The  most  important  is,  of  course,  the  main  feed  pump,  as 
that  has  to  do  the  brunt  of  the  work.  It  is  customary  to 
make  this  pump  of  the  duplex  type — that  is,  having  two  steam 
cylinders  and  two  water  cylinders,  so  arranged  that  the  valve 
gear  of  each  steam  cylinder  is  worked  from  the  crosshead  of 
the  other  pump.  Some  engineers  prefer  the  simplex  type,  and, 
in  my  opinion,  there  is  really  very  little  choice,  except  that 
the  simplex  type  costs  less  and  occupies  comparatively  less 
space.  The  choice  between  horizontal  and  vertical  pumps  is 
also  largely  a  matter  of  opinion,  as  there  are  engineers  of 
equal  standing  who  have  preference  for  both  types.  The  best 


FEED    WATER   FILTERS,    PUMPS    AND    INJECTORS  115 

feed  pump  is  the  one  that  gives  the  least  trouble  and  is  the 
most  reliable,  no  matter  whether  it  is  simplex,  duplex,  hori- 
zontal or  vertical." 

"Which  one  is  it?"  inquired  Schmidt. 

"That's  something  you  will  have  to  learn  for  yourself,  from 
your  own  practical  experience,"  answered  McAndrew.  "I 
have  heard  good  engineers  argue  themselves  black  in  the  face 
as  to  the  relative  merits  of  different  types  of  pumps,  and  at  the 
end  neither  convinced  the  other  that  he  was  right. 

"Everybody  will,  however,  agree  that  a  main  feed  pump 
should  be  made  as  simple  and  strong  as  possible;  that  its 
water  cylinders  should  be  made  of  solid  composition  if  you 
can  afford  it;  that  its  steam  valve  gear  can  be  readily  adjusted, 
and  that  it  keeps  running  constantly  without  much  watching." 

"How  is  it,"  inquired  Nelson,  "that  a  pump  using  steam  of 
boiler  pressure  can  force  water  into  the  boiler  against  the 
same  pressure?" 

"That  is  very  simple,"  replied  McAndrew,  "as  a  boiler  feed 
pump  is  somewhat  on  the  principle  of  a  lever — that  is,  the 
steam  cylinders  are  always  larger  than  the  water  cylinders. 
For  example,  a  common  proportion  for  an  ordinary  feed  pump 
is  to  have  steam  pistons  8  inches  in  diameter  driving  water 
pistons  or  plungers  5  inches  in  diameter.  Nelson,  what  would 
be  the  leverage  in  a  pump  proportioned  like  that?" 

"Why,  let  me  see,"  replied  Nelson.  "Oh!  Yes,  it  would 
be  i  3/5  times  as  much  pressure  on  the  steam  piston  as  it  is 
against  the  water  piston." 

"Oh,  no!"  smilingly  said  the  instructor,  "you  are  wrong — 
we  are  not  dealing  with  straight  lines  in  this  case;  if  it  were 
a  bar  lever  we  were  using  to  force  the  water  into  the  boiler 
your  answer  would  be  correct,  but  cylinders  have  circular  pis- 
tons, so  the  proportion  between  them  varies  with  the  squares 
of  the  diameters." 

"What's  that  mean,  sir?"  said  Nelson. 


n6  MC  ANDREW'S  FLOATING  SCHOOL 

"By  the  square  of  any  number  is  meant  the  product  ob- 
tained by  multiplying  the  number  by  itself.  Thus  the  square 
of  5  is  25  and  the  square  of  8  is  8  times  8,  or  64;  hence  the 
leverage  we  gain  in  this  particular  pump  is  equal  to  64  divided 
by  25,  or  2.56.  In  other  words,  there  is  a  load  on  the  steam 
piston  of  2.56  times  that  necessary  for  the  water  piston  to 
exert  a  force  equal  to  the  boiler  pressure.  This  proportion 
is  found  to  be  ample  to  insure  the  water  being  forced  into  the 
boiler  against  the  boiler  pressure,  friction  in  the  feed  pipes, 
check  valve,  etc.  Always  remember  the  rule  I  have  given  you 
about  comparing  things  having  circular  sections  and  you 
won't  fall  into  the  error  I  once  saw  a  man  make  of  fitting  two 
2-inch  drains  to  carry  off  the  water  put  into  a  tank  by  one 
4-inch  supply  pipe.  Tell  me  quickly,  O'Rourke,  how  many 
2-inch  drains  should  he  have  fitted?" 

"Four,  of  course,"  replied  the  Hibernian. 

"Fine  work !"  said  McAndrew. 

"A  good  guess,"  sneered  Schmidt. 

"There  is  usually  only  one  suction  pipe  and  one  discharge 
pipe  to  the  main  feed  pump,  so  that  it  will  draw  water  from 
the  feed  tank  and  discharge  into  the  main  feed  line  only. 
There  can  then  be  no  complication  and  no  danger  from  open- 
ing the  wrong  valves  when  the  pump  is  first  started  up.  A 
properly  proportioned  pump  should  work  easily  and  quietly. 

"The  auxiliary  feed  pump  is,  as  you  probably  know,  used  in 
case  the  main  feed  pump  breaks  down.  Many  people  call  this 
the  'donkey  pump,'  just  for  what  reason  I  do  not  know." 

"I  know  why  that  old  pump  on  this  ship  is  called  a  'donkey' 
— it's  because  it  bucks  and  kicks  so  much,"  suggested 
O'Rourke. 

"It  must  do  that  when  you  are  running  it,  then,"  retorted 
McAndrew.  "I  never  saw  it  act  that  way.  It's  all  in  knowing 
how  to  run  a  pump — you  probably  tried  to  start  it  without 


FEED    WATER   FILTERS,    PUMPS   AND   INJECTORS  1 17 

opening  any  of  the  discharge  valves.  I  think  the  'donkey' 
must  have  been  on  the  other  end. 

"The  'donkey  pump'  is,  of  course,  used  for  many  other  pur- 
poses than  as  a  boiler  feeder.  It  generally  has  four  or  five 
suctions  and  as  many  discharges.  It  can  be  used  for  pumping 
out  the  bilges,  pumping  out  the  boilers,  for  fire  purposes  and 
for  washing  down  decks.  When  you  use  this  pump  you  must 
be  very  careful  to  see  that  you  open  the  right  valves.  I  re- 
member catching  one  oiler  who  was  on  this  ship  pumping  bilge 
water  into  one  of  the  boilers  simply  because  he  had  opened 
the  wrong  suction  valve.  I  fired  him  at  once,  as  there  is  no 
place  on  this  or  any  other  steamship  for  such  careless  people. 

''The  auxiliary  or  'donkey'  pump  is  frequently  a  duplicate 
in  construction  of  the  main  feed  pump,  but  if  possible  the 
water  end  should  be  of  composition  on  account  of  handling 
salt  water.  On  all  well-designed  feed  pumps  there  is  an  air 
chamber,  both  on  the  suction  and  discharge  sides.  These  an- 
swer the  purpose  of  a  cushion  for  taking  up  the  shock.  Water 
is  practically  non-compressible,  so  that  a  sudden  stroke  of 
the  pump  acts  like  a  hammer  on  the  whole  pipe  system  unless 
there  is  an  air  chamber  wherein  the  air  is  compressed  like  a 
spring.  No  work  is  lost,  but  the  shock  of  impact  is  prevented. 

"There  is  another  method  of  feeding  water  into  a  steam 
boiler  besides  the  main  and  auxiliary  feed  pumps,  and  it  is  of 
such  importance  that  every  ship  should  be  fitted  with  at  least 
one.  This  is  known  as  the  'injector' — an  apparatus  which 
occupies  very  little  space  but  is  highly  efficient  and  often  very 
useful.  Fig.  24  is  a  sketch  of  an  ordinary  type. 

"In  the  figure  shown,  the  steam  is  admitted  through  the  pipe 
B,  the  entrance  to  the  body  of  the  injector  being  controlled 
by  the  valve  which  is  operated  by  the  handle  K.  When  this 
valve  is  opened,  the  steam  rushes  through  the  contracting  noz- 
zle 5.  'The  air  in  the  space  around  the  two  openings  shown 
is  mixed  with  the  steam  and  forms  a  partial  vacuum  sufficient 


Ho  MC  ANDREWS   FLOATING   SCHOOL 

to  draw  in  the  water  through  the  pipe  B.  This  water  com- 
bines with  the  steam  and  passes  into  the  combining  and  de- 
livery tube  C  D.  The  steam  is  condensed  in  this  tube  by  con- 
tact with  the  water,  and  the  jet  thus  formed  is  given  a  very 
high  velocity,  ample  to  lift  the  check  valve  and  force  it  into 
the  boiler.  It  is  really  the  energy  of  the  inrushing  steam 
which  gives  the  water  sufficient  momentum  to  carry  it  into 


FIG.    24. INJECTOR. 

the  boiler.  The  great  advantage  of  such  a  device  is  that  it 
acts  as  a  feed  water  heater,  the  water  going  into  the  boiler 
being  heated  by  the  steam  which  gave  it  the  momentum. 

"For  some  reason  or  another,  people  who  locate  injectors 
never  seem  to  get  them  piped  up  right.  They  should  be 
arranged  so  that  the  lift  of  the  water  will  be  very  small — not 
over  4  or  5  feet  at  the  greatest — and  the  discharge  pipe  to  the 
boiler  should  be  as  direct  as  possible  so  as  to  avoid  any  sharp 
bends.  You  have  all  heard  the  expression  that  'four  round 
turns  are  equal  to  a  blank  flange.'  That  is  not  exactly  so, 
but  it  is  nevertheless  true  that  every  round  turn  or  right- 
angled  bend  in  a  pipe  greatly  increases  the  friction  of  the 
water  passing  through  it. 


FEED    WATER   FILTERS,    PUMPS    AND    INJECTORS  I IQ 

"In  recent  years  engineers  generally  recognize  the  great  ad- 
vantage of  a  feed  water  heater,  so  that  no  new  vessel  is  turned 
out  without  one  of  these  aids  to  economy.  Ten  or  fifteen 
years  ago  it  was  not  generally  the  practice  to  fit  a  device  for 
warming  the  feed  water,  but  now  one  of  the  greatest  prob- 
lems which  confront  all  marine  engineers  is  to  get  the  great- 
est amount  of  work  out  of  the  least  amount  of  coal.  No  sin- 
gle apparatus  connected  with  marine  machinery  has  done  more 
to  produce  economy  of  fuel  consumption  than  the  feed  water 
heater,  a  device  primarily  to  utilize  heat  which  has  heretofore 
been  wasted  through  the  discharge  water  from  the  condenser. 
Many  devices  have  been  invented  to  heat  the  feed  water  by 
means  of  the  waste  gases  from  the  furnaces,  but  the  liability 
of  accidents  to  the  piping  thus  employed  has  practically  put 
them  out  of  use.  Hence,  nowadays,  it  is  almost  the  invariable 
practice  on  steam  vessels  to  have  the  feed  water  heated  by 
means  of  a  portion  of  the  exhaust  steam  from  the  auxiliaries, 
such  as  the  dynamos,  feed  pumps,  air  pump  (when  indepen- 
dent), etc.  The  best  form  of  feed  water  heater  of  this  class 
is  where  the  steam  does  not  come  in  contact  with  the  feed 
water.  In  other  words,  the  modern  feed  water  heater  is  prac- 
tically a  small  surface  condenser  where  the  feed  water  is  the 
circulating  medium.  These  are  of  various  types,  some  having 
straight  tubes  with  tube  sheets  like  an  ordinary  condenser, 
and  others  having  spiral  coils  connected  to  manifolds  at  the 
ends.  Heat  from  the  exhaust  steam  is  thus  transmitted  to  the 
feed  water,  so  that  it  is  possible  to  have  the  feed  water  enter 
the  boilers  at  as  high  a  temperature  as  240  or  250  degrees 
Fahrenheit." 

"I  thought  water  boiled  at  212  degrees,"  suggested  one  of 
the  class. 

"So  it  does,"  said  McAndrew,  "under  atmospheric  pressure 
only,  but  I  have  previously  pointed  out  to  you  that  the  boiling 
point  of  water  varies  with  the  pressure,  and  in  this  case  the 


I2O  MC  ANDREW  S    FLOATING    SCHOOL 

pressure  of  the  feed  water  is  higher  even  than  that  of  the 
steam  in  the  boiler." 

"Where  does  all  the  saving  come  in?"  inquired  Nelson. 

"I'll  show  you,"  said  the  instructor,  "as  it  is  quite  simple. 
We  will  suppose  that  we  are  using  steam  at  a  boiler  pressure 
of  180  pounds  per  square  inch,  and  that  the  feed  water  we 
have  been  using  is  only  100  degrees,  rather  cold,  but  still  it 
is  such  as  is  sometimes  used  when  great  care  is  not  exer- 
cised by  regulating  the  circulating  pump.  Now  suppose  we 
have  yielded  to  common  sense  and  fitted  the  vessel  with  a  feed 
water  heater  of  the  exhaust  steam  variety,  and  we  find  by  the 
thermometer  in  the  feed  pipe  that  the  water  is  entering  the 
boiler  at  an  actual  temperature  of  230  degrees  Fahrenheit.  We 
have  thus  caused  a  gain  of  130  degrees  Fahrenheit.  From  the 
'Steam  Tables'  we  find  that  steam  at  180  pounds  pressure  con- 
tains 1,198  B.  t.  u.  By  a  simple  calculation  we  then  find  how 
much  is  saved,  thus: 

Total  heat  in  I  pound  of  steam 1,198 

Heat  in  feed  water  as  used  originally  (100  —  32)  ...        68 


Heat  required  to  form  I  pound  of  steam  under  old 

conditions    . . . . 1,130 

Under  the  new  conditions  we  have  saved  230 — 100=130 
B.  t.  u.'s,  and  we  find  that  we  now  only  have  to  use  1,130 —  130 
or  1,000  B.  t.  u.'s  for  a  pound  of  steam.  To  find  the  ratio  of 
saving  we  divide  130  by  1,130  and  it  gives  11.5  percent.  Thus, 
if  the  ship  has  been  using  100  tons  of  coal  for  a  certain  run 
between  ports,  it  will  be  found  after  the  feed  water  heater  is 
fitted  that  88.5  tons  will  do  the  same  work.  At  $3  (125.  6d.) 
per  ton  there  will  be  a  saving  each  trip  amounting  to  $34.50 
(£7  33.  9d.).  For  100  trips  a  year  the  saving  in  coal  would 
be  $3,450  (£707),  or  more  than  enough  to  pay  for  the  new 
heater  the  first  year  it  is  used. 


FEED    WATER   FILTERS,    PUMPS    AND   INJECTORS  121 

"The  saving  in  fuel  is  not  the  only  benefit  to  be  derived,  as 
the  use  of  hot  feed  water  undoubtedly  prolongs  the  life  of 
the  boiler  and  prevents  many  leaks  in  the  seams  which  result 
from  the  use  of  cold  feed  water.  We  might  compare  the  bad 
effects  of  the  use  of  cold  feed  water  in  boilers  to  the  bad 
effect  on  a  man's  health  of  drinking  too  much  ice  water." 

"Would  it  make  his  seams  leak?"  asked  O'Rourke. 

"No.  But  it  often  makes  his  stomach  ache,  and  he  will  not 
last  as  long  as  the  man  who  slakes  his  thirst  with  water  only 
moderately  cold. 

"We  have  now  followed  the  feed  water  through  its  various 
manipulations,  and  it  is  prepared  to  enter  the  boiler,  except 
for  one  important  essential,  and  that  is  taking  the  air  out 
of  it.  Many  of  the  ills  which  befall  the  interior  surfaces  of 
boilers  are  due  to  the  air  which  enters  with  the  feed  water. 
There  is  not  in  general  use  any  simple  device  to  accomplish 
this,  however,  as  designing  engineers,  as  a  rule,  do  not  pay 
much  attention  to  this  important  matter.  If  a  pet-cock  is 
fitted  at  some  bend  in  the  pipe,  or  if  some  obstruction  is  fitted 
in  the  pipe,  considerable  of  this  air  can  be  blown  off,  and 
there  are  also  certain  automatic  devices  which  can  be  used 
for  blowing  out  the  entrapped  air.  In  watertube  boilers  where 
the  feed  water  enters  above  the  surface  of  the  boiler  water 
in  the  steam  drum,  the  air  is  released  to  a  considerable  extent 
by  having  the  feed  water  discharge  against  a  small  hood  over 
the  feed  pipe  nozzle,  so  that  it  enters  the  boiler  in  a  spray, 
the  air  becoming  separated  and  being  carried  off  with  the 
steam.  There  can  be  little  corrosion  in  boilers  without  the 
oxygen  in  the  air,  so  that  the  exclusion  of  air  from  the  water 
tends  greatly  to  reduce  the  pitting  and  corrosion. 

'The  feed  pipes  leading  from  the  feed  water  heater  to  the 
boilers  are  usually  made  of  seamless  drawn  brass  or  copper, 
and  should  run  as  nearly  straight  as  possible  to  avoid  friction. 
These  pipes,  as  far  as  possible,  should  be  run  where  they  are 


122  MC  ANDREW  S   FLOATING    SCHOOL 

easily  accessible  in  order  to  detect  any  leaks,  and  by  all  odds 
the  joints  should  be  located  where  they  will  be  easily  accessi- 
ble for  putting  in  new  gaskets,  as  a  leaky  joint  in  a  feed  pipe 
is  intolerable." 

"What's  that?"   said   O'Rourke. 

"That  means  something  that  we  cannot  stand  for,  very  much 
like  some  of  your  questions." 


CHAPTER  XIV 

Evaporators  and   Distillers 

"Which  one  of  you  knows  the  difference  between  an  evapo- 
rator and  a  distiller?"  said  McAndrew,  at  the  commencement 
of  the  evening's  lecture.  Before  any  of  the  rest  of  the  class 
could  reply,  the  ever-ready  O'Rourke  blurted  out,  "One  of  'em 
makes  dried  apples  and  the  other  makes  booze." 

"You  are  always  talking  about  something  that  is  most  fa- 
miliar to  you,  O'Rourke,"  sarcastically  replied  the  instructor; 
"while  it  is  true  that  'booze'  is  distilled,  we  are  dealing  with 
water  exclusively  just  now. 

"You  may  remember  that  when  we  had  the  subject  of  boilers 
under  consideration,  I  told  you  that  nowadays  only  fresh 
water  is  used  in  the  boilers.  The  steam  from  the  engine  is 
condensed  over  and  over  again  and  pumped  back  into  the 
boilers;  but  in  spite  of  all  the  precautions  the  engineer  can 
take,  there  is  more  or  less  of  the  water  lost  on  account  of 
leakages  around  the  boilers,  at  the  pipe  joints,  and  around  the 
stuffing-boxes  of  the  main  engines  and  the  auxiliaries.  Just 
how  much  this  leakage  amounts  to,  it  is  hard  to  estimate,  but 
a  goodly  supply  of  fresh  water  should  be  carried  in  the  ship's 
tanks  to  make  up  the  deficiency  of  feed.  When  that  is  used 
up,  as  it  generally  is  after  five  or  six  days'  steaming  on  most 
vessels,  then  we  have  to  have  other  means  for  furnishing  the 
fresh  water.  Of  course,  there  is  always  as  much  salt  water 
to  be  had  as  you  may  want,  but  the  problem  is  to  extract  the 
solid  matter  from  the  sea  water  so  that  it  will  not  be  de- 
posited on  the  heating  surfaces  of  the  boilers.  For  this  pur- 


124  MC  ANDREWS   FLOATING    SCHOOL 

pose  the  evaporator  is  used,  and  you  may  as  well  understand 
that  an  evaporator  is  simply  a  boiler  which  uses  steam  to  gen- 
erate steam  from  sea  water.  The  donkey  boiler  or  one  of 
the  main  boilers  could  be  used  for  evaporating  purposes  but 
for  the  fact  that  the  scale  would  be  deposited  on  their  heat- 
ing surfaces,  which  are  difficult  to  clean.  Hence  the  most  suc- 
cessful evaporator  is  the  one  that  is  easiest  to  clean.  By  using 
steam  from  the  main  boilers  to  generate  steam  in  the  evapo- 
rator, no  fresh  water  is  wasted,  as  the  steam  from  the  inside 
of  the  coils  is  condensed  and  passed  back  into  the  feed  tank 
or  condenser. 

"The  coils  or  tubes  of  an  evaporator  are  usually  arranged 
so  that  they  can  be  pulled  out  or  gotten  at  quite  readily  for 
cleaning  purposes,  for  after  only  a  day's  use  they  are  usually 
quite  heavily  incrusted  with  scale.  Scaling  evaporator  coils 
at  sea  is  a  delightful  job,  and  I  am  sure  that  you,  O'Rourke, 
will  be  tickled  to  death  to  do  your  share  of  it." 

"Huh !"  said  that  worthy,  "I  have  already  done  one  trick  at 
that  business  the  last  ship  I  was  on.  I  worked  so  hard  at  it 
that  I  punched  a  hole  through  one  of  the  coils,  and  the  first 
assistant  told  me  I  was  too  strong  for  such  scientific  work." 

"The  chances  are  you  did  it  on  purpose  to  get  out  of  work," 
said  McAndrew,  "but  that  shows  you  that  care  must  be  taken 
in  scaling  evaporator  coils,  as  they  are  usually  made  of  brass 
or  copper,  and,  naturally,  are  as  thin  as  they  can  well  be  made 
in  order  to  better  transmit  the  heat.  The  shell  of  the  evapo- 
rator is  made  of  steel,  about  the  same  as  you  would  build  a 
small  boiler,  only  it  is  a  good  idea  to  add  at  least  one-eighth 
of  an  inch  to  the  thickness  of  the  plate  in  order  to  allow  for 
the  excessive  corrosion  which  always  takes  place  around  the 
water-line. 

"There  is  quite  a  knack  in  running  an  evaporator,  as  you 
'will  find  from  experience.  The  principal  thing  to  guard  against 
is  excessive  foaming.  If  the  water  is  carried  too  high  in  the 


EVAPORATORS   AND   DISTILLERS  125 

glass,  it  will  boil  up  and,  mixing  with  the  steam,  will  be  car- 
ried over  with  it.  For  some  reason  the  water  in  an  evaporator 
foams  more  than  it  does  in  a  boiler  of  the  same  size,  hence 
its  height  must  be  watched  carefully,  and  all  evaporators 
should  be  fitted  with  baffle  plates  and  dry  pipes.  If  the  de- 
tilled  water  is  being  run  into  a  tank  for  the  use  of  the  ship,  a 
little  carelessness  in  allowing  the  salt  water  to  lift  might  re- 
sult in  spoiling  a  whole  lot  of  good  drinking  water. 

"After  the  steam  is  generated  in  the  evaporator,  it  is  usually 
passed  into  the  main  condenser,  where  it  is  condensed  into 
water  along  with  the  exhaust  steam  from  the  engine,  and  thus 
makes  up  the  deficiency  in  the  feed  water." 

"Where  does  this  distilling  business  come  in?"  inquired 
Nelson. 

"Oh,  yes,"  replied  McAndrew,  "I  almost  forgot  to  tell  you 
that  on  shipboard,  as  well  as  on  shore,  the  distiller  is  used 
for  drinking  purposes,  only  that  the  ship's  product  is  exclu- 
sively pure  water.  A  ship's  distiller  is  in  reality  only  a  small 
condenser,  and  is  usually  made  of  copper  or  brass;  the  sea 
water  is  used  for  cooling  purposes,  and,  passing  on  the  out- 
side of  a  number  of  small  brass  or  Muntz  metal  tubes,  which 
have  been  carefully  tinned,  condenses  the  steam  from  the 
evaporator  into  fresh  water,  which  is  run  into  tanks  and  used 
for  drinking  or  culinary  purposes." 

"I  know  all  about  the  drinking  end  of  it,  but  what's  this 
'culinary'  stunt?"  inquired  O'Rourke. 

"If  you  ever  hung  around  the  galley  any,  you  must  have 
noticed  that  the  cook  uses  considerable  fresh  water  to  make 
coffee,  soup,  etc,"  replied  McAndrew;  "that's  'culinary'— per- 
haps I  should  have  said  'cooking'  purposes." 

"Oh !  I  see,"  said  O'Rourke ;  "the  difference  between  'cul- 
inary' and  'cooking'  is  about  the  same  as  the  difference  be- 
tween a  'cook'  and  a  'chef.' " 

"To  return  to  the  subject.    I  forgot  to  tell  you  that  the  feed 


^26  MC  ANDREW'S  FLOATING  SCHOOL 

•water  for  the  evaporator  should  not  be  taken  from  the  sea 
direct,  as  it  has  to  be  heated  up  to  the  boiling  temperature,  so 
it  is  customary  to  take  it  from  the  discharge  water  from  the 
main  condenser,  which  has  already  been  heated  up  to  between 
120  and  140  degrees;  there  is  thus  a  considerable  saving  of 
heat  units  by  using  the  discharge  water  instead  of  the  cold 
sea  water. 

"Some  ships  have  several  evaporators  in  series,  the  steam  in 
the  first  one  being  raised  to  60  or  80  pounds  pressure  and 
then  passed  along  to  the  next  evaporator,  where  it  is  used  to 
generate  steam ;  the  steam  in  the  second  evaporator  is  carried 
at  a  pressure  of  from  10  to  15  pounds,  and  this,  in  turn,  is 
used  to  generate  steam  in  a  third  evaporator,  wherein  the 
steam  is  sometimes  at  a  pressure  below  that  of  the  atmosphere, 
but  it  readily  flows  into  the  main  condenser,  where  the  vacuum 
is  less.  Such  an  apparatus  is  known  as  a  triple-effect  evapo- 
rator, and  there  is  a  considerable  saving  by  such  means.  How- 
ever, the  first  cost  is  so  great  that  it  is  but  seldom  used. 

"I  must  also  tell  you  of  a  good  wrinkle  in  scaling  an  evapo- 
rator where  the  coils  are  of  the  spiral  type.  A  sudden  change 
of  temperature  will  tend  to  crack  the  scale,  so  that  by  a  slight 
tapping  with  a  wooden  mallet  it  will  drop  off  readily.  To  ob- 
tain this  sudden  change  of  temperature,  the  evaporator  should 
be  emptied  of  all  water  and  steam  turned  on  the  coils  until 
they  are  as  hot  as  it  is  possible  to  get  them.  Then  start  your 
evaporator  feed  pump  up  as  fast  as  it  will  run,  open  the  bot- 
tom blow  to  the  evaporator,  and  the  valve  connecting  the 
evaporator  to  the  main  condenser,  if  there  is  a  vacuum  in  it. 
The  cold  sea  water  will  then  rush  in  at  such  a  rate  as  to  give 
the  sudden  change  in  temperature  desired.  This  effect  can 
also  be  brought  about  by  heating  up  the  coils,  taking  off  the 
lower  manhole  plate  of  the  .evaporator,  if  such  is  provided, 
and  then  turning  the  fire  hose  on  the  coils." 


CHAPTER  XV 

Electricity 

"One  of  the  most  important  of  the  auxiliaries  on  board  a 
modern  steamer  is  the  dynamo  for  generating  electric  current 
for  lighting  and  ventilation  purposes.  The  study  of  electricity 
presents  a  very  large  subject  in  itself,  but  it  is  essential  that 
all  marine  engineers  have  at  least  a  fair  insight  into  the  general 
principles  involved.  I  will  therefore  give  you  a  few  hints  on 
the  subject  which  will,  I  hope,  be  of  interest  and  benefit  to  you. 

"In  commencing  my  remarks  on  the  subject,  I  will  ask  if 
any  of  you  know  what  electricity  is  ?" 

A  silence  followed  this  question,  which  was  finally  broken 
by  O'Rourke,  who  said,  "I  did  know  once,  but  I  have  clean 
forgotten  it." 

'Too  bad !  Too  bad,  entirely,"  said  McAndrew ;  "what  a 
loss  to  the  scientific  world !  To  think  that  you  once  knew  the 
mystic  key  to  this  great  question  which  no  living  man  has  ever 
solved,  and  that  you  have  forgotten  it !  You  certainly  should 
be  punished  for  such  monumental  carelessness  in  keeping  from 
the  public  the  true  answer  to  this  hitherto  unanswered  problem. 
Well,  we  will  have  to  continue  in  our  ignorance,  and  although 
no  one  but  O'Rourke  has  ever  really  known  what  electricity  is, 
we,  in  common  with  all  others,  will  have  to  devote  our  atten- 
tion to  studying  its  effects. 

"The  name  'electricity'  comes  from  the  Greek  word  'elec- 
tron,' meaning  amber,  as  it  was  from  rubbing  this  material 
with  a  catskin  that  the  phenomenon  was  first  noticed.  There 
are  three  principal  ways  of  generating  this  current,  as  it  is 


128  MC  ANDREW'S  FLOATING  SCHOOL 

generally  termed.  The  first  might  be  termed  'frictional  elec- 
tricity,' as  it  is  generated  by  rubbing  such  substances  as  glass 
and  silk  together;  you  may  also  have  noticed  its  effect  by 
scuffling  your  feet  on  a  woolen  carpet  and  then  touching  some 
metal,  such  a  a  gas  jet  or  brass  bed,  when  you  can  generally 
see,  hear  and  feel  a  slight  electric  shock.  This  method  of 
generating  electricity  is  not,  however,  used  practically. 

'The  second  method  might  be  termed  'chemical  electricity,' 
from  the  fact  that  a  current  is  set  up  by  immersing  two  differ- 
ent metals  in  a  chemical  solution.  Copper  and  zinc  are  most 
commonly  used,  as  it  is  found,  when  these  metals  are  immersed 
in  a  mild  solution  of  sulphuric  acid,  a  pronounced  flow  of  elec- 
trcity  is  set  up  between  them.  This  combination  is  known  as 
a  cell. 

"A  number  of  cells  form  a  battery,  and  electricity  from  such 
a  source  is  largely  used  for  operating  telegraph  lines,  alarm 
bells,  etc.  What  are  known  as  'dry  batteries,'  wherein  elec- 
trcity  is  formed  by  the  chemical  decomposition  of  zinc  in  the 
presence  of  carbon  surrounded  by  a  paste  made  of  plaster, 
flour  or  chemicals,  are  particularly  useful  on  shipboard,  as 
there  is  no  liquid  to  be  spilled  by  the  rolling  of  the  ship. 

"The  third  method  of  generation  might  be  termed  the  'mag- 
netic system.'  You  all  know  of  and  have  played  with  the  ordi- 
nary toy  horseshoe  magnet.  The  two  ends  of  a  magnet  are 
known  as  'poles,'  and  you  no  doubt  have  observed  that  there 
is  an  unseen  force  acting  between  these  poles,  sufficiently 
strong  to  attract  or  pick  up  small  pieces  of  metal,  and  that  it 
is  particularly  strong  in  picking  up  iron  or  steel.  This  ability 
of  attracting  pieces  of  metal  is  attributed  to  what  are  known 
as  lines  of  magnetic  force'  which  exist  in  the  magnet.  Some 
of  the  early  experimenters  discovered  that  if  certain  combina- 
tions of  wires  were  revolved  between  'these  poles  of  a  magnet 
— or  the  'magnetic  field,'  as  it  is  called — a  current  of  electricity 
would  be  set  up.  Proceeding  on  this  principle,  the  modern 


ELECTRICITY 


129 


dynamo  has  been  evolved.  I  will  not  attempt  to  mystify  you 
by  going  into  the  theory  of  how  this  is  done,  as  I  feel  quite 
sure  that  after  I  had  finished  you  would  probably  have  a  hazier 
idea  than  you  had  before,  so  I  will  confine  my  remarks  to  some 
of  the  practical  things  which  you  should  learn  about  the  sub- 
ject. 

'This  'magnetic  system*  of  producing  electricity  is  used  al- 
most exclusively  for  all  lighting  and  power  purposes.  The 
modern  dynamo  for  producing  current  is  to  all  intents  and 
•purposes  a  large  magnet,  and  the  bunches  of  wires  revolving 
between  its  poles,  and  hence  cutting  the  'lines  of  force,'  is 
known  as  the  'armature.'  The  current  is  collected  by  what  are 
known  as  'brushes,'  generally  blocks  of  carbon,  held  against 
the  revolving  metal. 

"I  do  not  expect  you  to  grasp  the  idea  of  electricity  imme- 
diately, as  very  few  people  do,  but  it  will  probably  help  you 
somewhat  to  compare  it  with  water  in  a  pipe  system.  In  such 
a  comparison  we  will  consider  the  dynamo  as  a  pump  forcing 
water  through  a  continuous  line  of  pipe  of  varying  diameter, 
according  to  the  flow  desired.  We  will  suppose  that  the  main 
leading  away  from  the  force  pump  is  divided  up  into  several 
branches,  and  that  from  each  of  these  branches  there  are 
numbers  of  small  spigots  from  vhich  the  water  is  being  drawn. 
We  all  know  that  no  water  will  flow  from  the  outlets  unless  a 
pressure  is  put  on  by  the  pump.  We  also  know  that  this  water 
is  being  used  at  the  various  outlets,  and  that  we  can  deter- 
mine how  many  gallons  per  minute  is  being  used  if  we  so 
desire.  You  can  also  readily  understand  that  the  water  will 
not  flow  through  the  pipe  line  as  readily  as  it  would  if  simply 
pumped  overboard  directly  from  the  discharge  valve,  on  ac- 
count of  the  friction  of  the  water  as  it  slides  or  flows  over  the 
inner  surfaces  of  the  pipes.  Now  we  must  imagine  that  elec- 
tricity is  being  used  instead  of  water.  The  wires,  proportioned 
according  to  the  amount  of  flow  required,  take  the  places  of 


13°  MC  ANDREW'S  FLOATING  SCHOOL 

the  pipe  and  its  branches.  The  electric  lights,  distributed  along 
the  branches,  take  the  places  of  the  spigots  in  the  pipe  line." 

"The  pressure  of  the  water  corresponds  to  what  is  known 
as  'electro-motive  force'  for  electric  currents,  and  the  unit  is 
known  as  the  'volt.'  Thus  we  have  on  the  switchboard  of  all 
electric  plants  a  Voltmeter,'  which  corresponds  to  the  pressure 
gage  in  a  pipe  line ;  in  other  words,  we  read  the  electric  press- 
ure from  the  voltmeter,  and  it  is  well  to  note  that  the  standard 
pressure  for  lighting  currents  on  shipboard  is  no  volts. 

"The  resistance  to  the  flow  of  water  through  pipes  corre- 
sponds to  the  resistance  of  the  flow  of  electricity  through 
wires,  and  the  unit  of  this  resistance  is  called  an  'ohm.' 

"The  rate  with  which  water  flows  through  a  pipe  in  a  given 
time  is  expressed  in  so  many  gallons  per  minute ;  in  electricity 
the  rate  of  flow  is  expressed  in  a  unit  known  as  an  'ampere,' 
which  means  the  amount  of  current  produced  by  a  pressure  of 
one  volt  acting  against  a  resistance  of  one  ohm. 

"Electric  power,  like  mechanical  power,  must  take  into  con- 
sideration the  element  of  time,  and  the  unit  of  this  kind  of 
power  is  known  as  the  'watt,'  which  is  the  power  produced  by 
a  current  of  one  ampere  at  a  pressure  of  one  volt  for  one 
second." 

"Where  do  they  get  all  these  funny  names  like  volt,  ampere 
and  ohm?"  inquired  Pierce. 

"They  are  derived  from  the  names  of  the  early  scientists  who 
studied  this  subject,  and  in  this  way  their  fame  will  be  handed 
down  to  future  generations.  Volt  conies  from  the  Italian 
named  Volta,  who  was  an  early  experimenter  in  the  subject. 
Ampere  was  another  early  scientist,  and  you  ought  to  know 
that  Watt  was  the  inventor  of  the  steam  engine.  If  you  had 
been  around  in  those  days,  and  made  the  experiments,  the  unit 
of  pressure  might  have  been  a  'pierce'  instead  of  a  'volt.'  " 

"I'll  bet,"  said  Smith,  "that  the  unit  of  resistance  or  friction 


ELECTRICITY  !^z 

would  have  been  an  'O'Rourke'  if  he  had  been  around  in  those 
days." 

"One  thing  sure,"  replied  McAndrew,  "the  unit  of  work 

'ampere' — would  never  have  been  displaced  by  anything  that 
sounded  like  an  'O'Rourke.' 

"The  'watt'  is  a  much  smaller  unit  than  the  horsepower, 
and,  in  fact,  it  takes,  theoretically,  746  watts  to  equal  one 
horsepower.  That  doesn't  mean  that  a  one-horsepower  engine 
•would  produce  that  many  watts,  as  there  are  too  many  losses 
between  the  two,  but  it  is  known  as  the  theoretical  equivalent. 
In  speaking  of  the  rated  power  of  a  dynamo  or  generator,  the 
general  term  is  20  K.W.,  50  K.W.,  etc.,  as  the  case  may  be. 
The  K.  means  kilo,  the  Greek  word  for  one  thousand,  so  that 
a  20  K.W.  machine  means  one  that  is  capable  of  producing 
20,000  watts. 

"To  utilize  electricity  for  lighting  purposes,  it  was  necessary 
to  invent  an  electric  lamp,  and  this  fell  to  the  lot  of  Edison, 
an  American  inventor,  who,  after  many  months  of  experiment- 
ing, found  that  a  filament  of  carbonized  bamboo,  placed  in- 
side a  glass  bulb  from  which  all  the  air  had  been  exhausted, 
would  heat  up  to  an  incandesence  when  an  electric  current  was 
passed  through  it.  If  the  air  is  not  exhausted  from  the  bulb, 
the  oxygen  in  the  air  would  cause  combustion,  which  would 
burn  up  the  filament  almost  instantly.  Many  metallic  sub- 
stances are  now  used  for  filaments,  and  are  known  as  'tung- 
sten,' 'mazda,'  'tantalum,'  etc.  These  are  much  more  efficient 
than  the  old-style  carbon-filament  lamps,  that  is,  they  give 
much  more  light  for  the  same  amount  of  current  used.  The 
ordinary  carbon-filament  i6-candlepower  lamp  is  generally 
used  on  shipboard ;  this  lamp  requires  about  H  ampere  of  cur- 
rent or  55  watts.  If  we  know  the  voltage  of  a  current  and 
the  amperage,  how  do  we  tell  how  many  watts  will  be  used?" 
asked  McAndrew  of  the  class. 


132  MC  ANDREW  S    FLOATING    SCHOOL 

"Wait  until  you  get  the  bill  from  the  electric  lighting  com- 
pany," suggested  O'Rourke. 

"You  can't  be  too  sure  of  that,"  replied  the  instructor,  "as 
most  people  have  an  idea  that  gas  bills  and  electric  light  bills 
are  not  made  out  on  a  strictly  scientific  basis.  The  right  way  to 
ascertain  that  fact  is  to  remember  that  the  watts  are  equivalent 
to  the  volts  multiplied  by  the  amperes.  In  this  case  we  have 
no  x  */>,  which  equals  55.  If  we  were  using  20  amperes  of 
current  at  a  pressure  of  10  volts  the  result  would  be  20  x  10, 
or  200  watts. 

"An  ordinary  i6-candlepower  lamp,  using  55  watts  of  cur- 
rent, will  require,  on  an  average,  i-io  horsepower  at  the  gen- 
erating engine,  so  I  want  to  impress  upon  you  the  importance 
of  turning  off  electric  lamps  which  are  not  needed  in  any 
part  of  the  ship,  as  they  soon  eat  into  the  coal  pile  to  a  con- 
siderable extent,  for  every  hour  that  a  i6-candlepower  lamp 
is  burned  there  is  nearly  a  pound  of  coal  used  under  the 
boilers. 

"I  want  to  call  your  attention  to  the  instruments  used  on 
the  switchboard,  which  is  the  name  of  the  apparatus  by  means 
of  which  the  current  is  distributed.  The  whole  electric  light 
system  is  divided  up  into  circuits  or  branches,  corresponding 
to  the  different  parts  of  the  ship.  For  example,  there  is  usually 
a  complete  circuit  for  the  engine  room,  one  for  the  fire  room, 
one  for  the  social  hall,  etc.  If  these  were  water-pipe  connec- 
tions there  would  be  a  valve  in  the  pipes  at  both  ends  of  the 
circuit.  For  electricity,  what  is  known  as  a  switch  or  cut-out 
is  used,  and  generally  located  on  the  switchboard.  They  are 
usually  of  the  double  pole  type,  that  is,  they  cut  out  both  the 
sending  side  and  the  return  side  simultaneously. 

"Unlike  water,  electricity  is  liable  to  sudden  fluctuations  of 
both  pressure  and  volume ;  unless  some  means  of  easement  is 
provided,  damage  is  liable  to  result  to  the  wiring  or  fixtures. 
Hence  at  various  points  in  the  circuit  the  current  is  made  to 


ELECTRICITY  133 

pass  through  short  lengths  of  some  fusible  alloy,  which,  when 
subjected  to  an  unusual  current,  melts  and  breaks  the  circuit. 
These  are  made  in  two  types,  the  link  and  cartridge ;  one  is  a 
plain  wire,  and  the  other  is  a  wire  encased  in  a  fiber  tube. 
The  action  in  this  case  is  similar  in  effect  to  the  blowing  off 
of  a  safety  valve. 

"The  ammeter  is  an  instrument  for  indicating  by  a  needle  on 
a  dial  the  amount  of  current  being  used,  which  varies,  of 
course,  with  the  number  of  lights  and  fans  in  use. 

"The  voltmeter,  or  pressure  gage,  has  the  same  function  as  a 
steam  gage  on  the  boiler. 

"The  rheostat  is  an  instrument  for  using  up  surplus  energy 
or  current,  and  consists  of  a  series  of  coiled  wires  which  can 
be  connected  up  in  the  circuit  by  moving  a  handle  across  the 
contact  points.  You  probably  know  that  when  the  main  engine 
of  a  ship  is  required  to  run  slowly,  and  the  boilers  temporarily 
making  more  steam  than  can  be  handled  by  the  engine,  it  is 
customary  to  open  what  is  known  as  the  'bleeder  valve'  from 
the  main  steam  pipe,  which  allows  the  high-pressure  steam  to 
blow  directly  into  the  condenser.  This  is  practically  the  same 
purpose  for  which  the  rheostat  is  used,  the  surplus  current  be- 
ing dissipated  by  the  increased  resistance  of  the  coils  of  wire 
which  disposes  of  the  electric  energy  in  the  form  of  heat. 

"Now  a  word  about  wiring  to  transmit  the  current  to  the 
points  where  it  is  needed.  As  copper  offers  less  resistance  to 
the  flow  of  electricity  than  any  other  metal  of  reasonable  cost, 
it  is  used  almost  universally.  In  laying  out  the  wiring  for  the 
ship,  the  sizes  are  determined  to  suit  the  quantity  of  electricity 
to  be  used  in  about  the  same  manner  that  we  would  proportion 
piping  for  the  distribution  of  steam  or  water.  Small  wires 
are  made  single,  and  for  larger  currents  it  is  customary  to  use 
a  number  of  small  wires  either  parallel  or  laid  up  in  the  form 
of  a  cable.  On  shipboard  it  is  of  the  first  importance  that  the 
wires  should  be  well  insulated,  that  is,  covered  with  a  sub- 


134 


MC  ANDREW  S    FLOATING    SCHOOL 


stance  which  prevents  entirely,  or  to  a  large  extent,  any  flow 
of  electricity  through  it.  The  best  and  most  used  of  such  sub- 
stances is  ordinary  rubber  covered  with  braided  silk  or  cotton 
to  make  the  whole  covering  waterproof.  Water  is  an  ex- 
cellent conductor  of  electricity,  and  hence  any  leakage  through 
the  covering  on  the  wires  will  rapidly  result  in  corrosion  of 
the  wires  and  leakage  or  short  circuiting  of  the  electric  cur- 
rent. In  the  first  marine  electric  installations  the  wires  were 
run  in  wooden  strips,  but  as  it  was  difficult  to  keep  them  tight, 


HHHH 


FIG.    24. — DISTRIBUTION    IN    PARALLEL 

the  almost  universal  practice  now  is  to  run  electric  wires  in 
iron  pipes  known  as  conduits.  Porcelain  is  another  excellent 
non-conductor  of  electricity,  hence  we  find  that  material  used 
for  various  kinds  of  electric  fittings  and  lamp  sockets. 

"The  wires  for  electric  lights  on  ships  are  usually  run  in 
what  is  known  as  'parallel,'  as  shown  in  Fig.  24. 

"Each  lamp,  you  will  notice,  is  tapped  off  between  the  two 
wires,  so  that  each  will  draw  a  sufficient  amount  of  electricity 
from  the  main  to  run  the  particular  lamp. 

"Other  uses  than  for  lighting  on  shipboard  are  fan  motors 
and  winch  motors." 


ELECTRICITY 


135 


"What  is  a  motor?"  inquired  one  of  the  class. 

"A  motor,"  said  McAndrew,  "is  simply  a  small  dynamo  run- 
ning backwards.  Electric  fans  are  driven  by  means  of  the 
current  passing  through  the  wire  wound  around  the  magnetic 
poles,  which  causes  the  armature  to  revolve.  The  fan  blades 
are  secured  to  an  extension  of  the  armature.  If  the  small 
armature  was  made  to  revolve  by  an  engine  or  other  source  of 
power,  the  motor  would  generate  electricity  instead  of  using 
it  up,  and  hence  become  a  small  dynamo. 

"In  closing  my  remarks  on  electricity,  I  want  to  impress 
upon  you  that,  although  it  is  not  known  definitely  what  it  is, 
its  effects  are  very  well  known,  and  there  is  no  great  mystery 
about  it.  You  do  not  get  something  for  nothing,  as  many  be- 
ginners are  apt  to  think.  For  all  electrical  energy  generated 
and  used,  there  is  a  still  greater  amount  of  mechanical  energy 
exerted  in  its  production.  If  the  current  comes  from  a  bat- 
tery, you  have  to  produce  it  by  the  disintegration  or  wasting 
away  of  the  zincs ;  if  from  a  dynamo,  it  takes  coal  to  produce 
it.  The  only  free  electricity  we  get  is  that  from  the  clouds  in 
the  form  of  lightning,  but  no  one  has,  as  yet,  found  a  method 
of  utilizing  currents  from  that  source." 

"What  about  Jersey  lightning?"  inquired  O'Rourke. 

"I  suppose  you  refer  to  the  New  Jersey  drink  known  as 
'applejack,'  and  if  that's  the  case,  I  haven't  heard  that  that  is 
free,  either,  but  I  understand  its  results  are  about  as  fatal  as 
the  lightning  we  get  from  the  clouds.  You  probably  know 
more  about  that  than  any  of  the  others  here." 


CHAPTER  XVI 

Pipes    and  Valves 

'The  school  will  be  in  order,"  demanded  McAndrew,  as  he 
entered  "Highbrow  Hall,"  it  having  been  dubbed  that  by 
O'Rourke.  The  cause  of  this  remark  was  a  heated  discussion 
which  was  being  carried  on  by  the  four  students  as  to  whether 
the  United  States  or  Germany  had  the  larger  navy.  Gus 
Schmidt  and  Nelson  were  maintaining  that  Germany  was  the 
more  powerful,  while  Pierce  and  O'Rourke  strenuously  in- 
sisted that  Uncle  Sam  was  the  superior  on  the  water. 

"Never  mind  about  the  navies  of  the  world,"  said  the  in- 
structor, "they're  big  enough  to  look  after  themselves — what 
you  boys  should  be  interested  in  is  to  be  of  some  use  to  the 
merchant  marine.  I  want  to  discuss  this  evening  the  subject 
of  pipes  and  valves.  We  have  dealt  with  boilers,  engines, 
pumps,  etc.,  and  now  we  want  to  connect  them  up.  This  is, 
therefore,  a  very  important  matter,  as  much  depends  in  the 
successful  operation  of  marine  machinery  on  having  proper 
pipes  to  carry  the  steam  and  water  and  proper  valves  to  con- 
trol them.  Piping  on  board  ship  can  be  divided  into  three  gen- 
eral classes,  i.  e.,  steam  pipes,  exhaust  pipes  and  water  pipes. 

"The  main  steam  pipe  system  is  naturally  of  the  greatest 
importance,  as  through  this  system  the  steam  is  passed  from 
the  boilers  to  the  main  engine. 

"The  material  generally  used  for  the  main  steam  pipe  is 
copper,  on  account  of  its  great  ductility,  the  ease  with  which 
it  is  worked  and  its  freedom  from  corrosion.  For  sizes  up  to 
10  and  12  inches  in  diameter  it  is  made  of  seamless  drawn 


PIPES    AND   VALVES 


137 


material  in  order  to  avoid  the  brazed  seam,  which  is  liable  to 
be  the  cause  of  leakages.  As  copper  expands  or  increases  in 
length  when  heated  up  to  the  temperature  of  the  steam  it  car- 
ries, great  care  is  exercised  by  designers  to  make  arrangements 
for  this  expansion  to  be  taken  up  without  damaging  the  pipe 
or  its  flanges.  One  method  of  accomplishing  this  is  by  means 
of  the  ordinary  'slip  joint,'  as  shown  in  this  sketch. 


FIG.     25. EXPANSION     JOINT 

"These,  however,  cause  considerable  work  in  order  to  have 
them  properly  packed,  and  have  been  known  to  pull  apart  and 
scald  people  who  happened  to  be  in  the  vicinity.  The  best 
method  is  to  lay  out  the  pipes  so  that  there  will  be  a  number 
of  large  curves  or  bends  in  their  length ;  the  expansion  then 
being  taken  up  by  the  slight  bending  of  the  pipes.  That  is  the 
reason  you  never  see  a  large  steam  pipe  run  straight.  As  all 
pipes  must  be  in  such  lengths  as  to  get  them  in  and  out  of  the 
spaces  they  occupy  for  the  purpose  of  making  repairs,  the  sec- 
tions must  be  securely  bolted  together.  This,  you  may  have 
noted,  is  accomplished  by  expanding  the  ends  of  the  pipes 
into  rings  of  cast  iron  or  composition,  called  flanges,  and  after 
putting  in  some  packing  between  the  flanges,  they  are  bolted 
up  tightly  together  by  means  of  a  number  of  bolts  of  sizes  to 
suit  the  diameter  of  the  flanges.  The  making  and  keeping 
tight  of  these  pipe  joints  is  one  of  the  most  serious  parts  of  an 
engineer's  business.  Various  kinds  of  patented  packings  are 
used  for  making  these  so-called  'gaskets'  for  pipe  joints;  many 


138  MC  ANDREW'S  FLOATING  SCHOOL 

of  them  are  excellent,  some  are  good,  and  others  are  not  worth 
two  hoots.  You  will  each  have  to  learn  from  your  own  ex- 
perience which  is  the  best  material  to  use,  but  be  sure  and  get 
the  kind  which  keeps  the  tightest  joint  and  lasts  the  longest." 

"Which  one  is  that?"  inquired  Nelson. 

"Ask  each  packing  agent  who  tries  to  sell  you  some,  and 
you  will  find  that  he  has  the  goods,"  was  the  reply.  "Some 
night  when  you  are  compelled  to  work  an  extra  watch  to  re- 
place a  blown-out  joint  over  the  top  of  a  hot  boiler,  just  make 
a  record  of  your  thoughts  regarding  that  particular  kind  of 
packing,  and  when  you  get  back  in  port  show  it  to  the  agent 
whom  you  patronized." 

"Wouldn't  we  have  to  write  those  thoughts  on  some  asbes- 
tos paper?"  inquired  O'Rourke. 

"I  think  you  would,"  said  McAndrew. 

"Main  steam  pipes  on  some  vessels  carrying  very  high-pres- 
sure steam  are  made  of  seamless  drawn  steel,  on  account  of  its 
strength  being  greater  than  that  of  copper.  The  disadvantages 
of  steel  for  piping  are  the  difficulty  in  making  easy  bends  and 
its  liability  to  corrosion.  The  flanges  on  steel  pipes  are  some- 
times made  solid  with  the  pipe,  and  this  makes  the  strongest 
job  obtainable  for  a  joint  of  this  kind. 

"Auxiliary  steam  piping  is  made  of  copper,  brass,  iron  or 
steel,  according  to  the  class  of  work.  Seamless  drawn  copper 
is  about  the  best  that  can  be  used,  while  ordinary  wrought  iron 
piping  with  screwed  joints  is  often  used  in  the  cheaper  kinds  of 
work. 

"Exhaust  piping  for  steam  is  made  of  copper  or  iron,  and  it 
only  differs  from  steam  piping  in  being  made  thinner,  as  it  does 
not  have  to  withstand  so  high  a  pressure. 

"Speaking  of  iron  piping,  O'Rourke,  did  you  ever  see  a  piece 
of  ^$-inch  pipe?" 

"Lots  of  it,"  replied  the  ever-ready. 

"Well,  I'm  glad  to  hear  it,"  said  McAndrew,  "you  are  prob- 


PIPES    AND  VALVES  139 

ably  the  only  one  living  who  has  ever  seen  that  size ;  as  a 
matter  of  fact  pipe  manufacturers  do  not  make  any  %-inch 
pipe  or  any  ^g-inch  pipe,  either.  Just  why  they  don't  I  am 
unable  to  say,  but  the  old-timers  who  originated  pipes  for  use 
around  gas  works  probably  had  good  reasons  for  not  doing 
so. 

"Just  jot  this  down  in  your  memories:  Pipe  sizes  are  ]/& 
inch,  *4  inch,  fy&  inch,  y2  inch,  ^4  inch,  i  inch,  \y\  inches,  il/t 
inches,  2  inches,  2l/2  inches,  3  inches,  3^  inches,  4  inches,  4^ 
inches,  5  inches,  and  above  that  in  even  inches.  If  any  one 
ever  tells  you  to  go  and  get  them  a  piece  of  i^-inch  pipe,  or 
any  other  size  which  is  not  in  the  list  I  have  given  you,  they 
are  trying  to  run  you.  Just  tell  them  that  the  storekeeper  is  all 
out  of  that  particular  size. 

"If  any  one  ever  asks  you  the  diameter  of  a  i-inch  pipe,  don't 
think  that  it  is  a  similar  question  to  'What  times  does  the 
12  o'clock  train  leave?'  for  it  is  not.  While  the  12  o'clock 
train  may  leave  at  12  o'clock,  a  i-inch  pipe  is  always  1.05 
inches  inside  diameter;  a  ^-inch  pipe  is  .62-inch  inside  diam- 
eter, or  nearly  ^  inch.  Here,  again,  the  old-time  gas  engineers 
got  in  their  work ;  but  if  you  don't  like  standard  sizes  you  can 
go  without  them;  they  have  come  to  stay,  and  you  might  as 
well  try  to  buy  cheese  by  the  yard  instead  of  by  the  pound  as 
to  get  manufacturers  to  change  these  old-established  standards. 

"For  high  pressures,  pipes  are  made  'extra  heavy'  and 
'double  extra  heavy/  but  the  outside  diameters  are  the  same, 
the  excess  metal  being  put  on  the  inside. 

"Brass  pipes  are  made  of  iron-pipe  size,  and  are  frequently 
used  in  small-sized  steam  and  exhaust  pipes.  Iron  and  brass 
pipes  are  not  bent  so  easily  as  copper  pipes,  hence  to  change 
direction  in  a  pipe  lead,  or  to  reduce  or  increase  sizes,  various 
standard  fittings  are  used.  These,  naturally,  are  made  of  what 
is  known  as  'malleable  iron' — a  cast  iron  which  is  not  as 
brittle  as  ordinary  cast  iron.  Hence  if  the  lead  of  the  pipe  is 


140  MC  ANDREW'S  FLOATING  SCHOOL 

to  change  at  right  angles,  an  'elbow'  is  used ;  if  one  pipe  is  to 
branch  off  at  right  angles  to  another  pipe,  a  'tee'  is  used;  if 
two  pipes  are  to  be  joined  together  for  permanent  use,  a 
'coupling'  is  used;  if  sections  of  piping  are  to  be  put  up  so  that 
they  can  be  taken  down,  'unions'  are  used,  and  let  me  say 
right  here  that  for  marine  work  you  can't  use  too  many 
'unions,'  as  they're  mighty  handy  fittings ;  then  there  are 
'plugs,'  'caps/  'reducers,'  and  various  other  devices  for  the 
.convenient  installation  of  piping,  all  of  them  made  with  stand- 
ard pipe  threads. 

"For  water  piping  on  board  ship,  copper  is  almost  always 
used  for  pipes  which  handle  salt  water,  although  in  some  cases 
for  bilge  pipes,  lead  is  used.  Copper  has  the  advantage  of  not 
being  corroded  by  salt  water,  and  as  it  can  be  bent  easily  it 
makes  an  ideal  material  for  such  purposes.  For  the  feed  pipes, 
seamless  drawn  brass  is  frequently  used  for  the  straight  parts 
and  copper  pipe  for  the  bends.  For  the  fire  main  seamless 
drawn  brass  is  the  best  material,  but  as  this  is  very  expensive 
it  is  seldom  used.  A  very  good  substitute  material  for  use  as 
fire  mains  is  wrought  iron  or  steel  lined  with  lead.  The  iron 
or  steel  furnishes  ample  strength  to  resist  the  pressure,  and 
the  lead  lining  prevents  corrosion  of  the  interior,  providing 
always  that  no  leaks  develop  through  the  lining." 

"What  do  you  mean  by  'seamless  drawn  ?'  "  asked  one  of  the 
class. 

"When  pipes  were  first  made  they  were  rolled  up  into  cylin- 
drical form  out  of  sheet  metal,  and  the  seam  brazed  in  the  case 
of  copper  and  riveted  for  iron  or  steel.  A  joint  of  either  kind 
is  an  element  of  weakness,  and  leaks  frequently  start  from 
imperfections  in  the  welding  or  brazing  of  the  joint.  Of  late 
years  the  art  of  drawing  metal  pipes  from  a  solid  block  or 
ingot  over  a  mandrel  has  taken  great  strides,  so  that  to-day  it 
is  possible  to  buy  either  steel  or  copper  pipes  of  any  size  up  to 
12  inches  and  over  in  diameter  which  have  been  drawn  solid, 


PIPES   AND  VALVES  141 

and  consequently  have  no  seams.  Although  at  present  the 
larger  sizes  of  seamless  pipe  cost  more  than  built-up  pipes, 
the  greater  safety,  due  to  the  absence  of  joints,  makes  it  ad- 
visable to  use  this  pipe,  especially  for  steam  and  water  piping 
subjected  to  high  pressures. 

"In  main  feed  pipes  on  board  ship  it  is  always  necessary 
to  make  them  in  several  lengths  to  facilitate  their  installation 
in  crowded  spaces,  and  to  make  them  accessible  for  repairs. 
The  location  of  flanges  joining  these  sections  together  should 
be  very  carefully  planned  out  in  order  to  provide  freedom  of 
access  in  making  new  joints.  When  a  leak  occurs  in  a  feed 
pipe  joint  it  must  be  repaired  very  quickly,  as  boilers  under 
steam  won't  run  long  without  water.  Every  .boiler  is,  of  course, 
provided  with  both  a  main  and  an  auxiliary  feed  connection, 
but  no  engineer  ever  feels  very  comfortable  while  even  one  of 
these  pipe  connections  is  out  of  order. 

"Bilge  pipes  are  sometimes  made  of  lead,  as  I  previously 
stated,  but  more  often  they  are  made  of  galvanized  iron  on 
account  of  the  less  cost.  In  connection  with  bilge  piping  it  will 
be  well  to  tell  you  something  about  the  methods  of  getting 
water  out  of  a  ship's  bilge,  as  every  marine  examiner  will  ask 
you  something  about  that.  The  usual  form  of  the  question  is, 
'State  how  many  means  there  are  for  getting  water  out  of  the 
bilges  ?'  Perhaps  you  can  answer  it  off-hand,  O'Rourke." 

"Sure,"  said  that  worthy.  "Start  the  donkey  pump,  and  if 
that  doesn't  do  the  trick  put  the  firemen  to  work  bailing  it  out 
with  buckets." 

"Starting  the  donkey  pump  would  do  for  ordinary  circum- 
stances, but  in  an  emergency,  if  you  were  put  to  work  bailing 
out  the  bilges,  I  am  afraid  the  ship  would  sink  before  you 
carried  more  than  two  or  three  bucketsful  up  the  ladders ;  that 
is,  if  you  didn't  work  any  faster  than  you  usually  do. 

"The  usual  method  of  pumping  out  bilges  is  by  the  inde- 
pendent bilge  pump  with  which  most  ships  are  furnished. 


142  MC  ANDREWS    FLOATING    SCHOOL 

This  pump  can  be  connected  to  all  compartments  of  the  ship 
through  the  manifold,  from  which  pipes  lead  to  all  bilges.  You 
may  have  noticed  that  valve  near  the  circulating  pump  which 
is  always  kept  closed,  and  should  be  locked  or  tied  shut.  In  a 
great  emergency,  such  as  the  ship  grounding  or  in  collision,  the 
main  circulating  pump  can  be  connected  so  as  to  pump  out  the 
bilges,  by  closing  the  main  injection  valves,  and  opening  this 
emergency  or  bilge  injection  valve,  as  it  is  termed.  On  most 
ships  the  auxiliary,  or  donkey  pump,  usually  is  connected  to  the 
bilge  manifold,  so  that  it  may  also  be  put  to  pumping  out  the 
bilges. 

"Many  ships  are  provided  with  what  is  known  as  a  'bilge 
ejector,'  whereby  a -jet  of  steam  starts  and  maintains  a  syphon 
effect  which  forces  the  bilge  water  up  and  overboard.  Such  a 
contrivance  is  too  wasteful  of  steam,  and  consequently  of  fresh 
water,  to  be  used  very  freely  on  vessels  plying  the  ocean.  If 
all  these  devices  fail  to  keep  the  water  in  check,  then  the  best 
thing  you  can  do  is  to  pack  your  grip  and  take  to  the  boats." 

"How  about  saying  your  prayers  ?"  inquired  O'Rourke. 

"I  don't  think  that  would  work  in  your  case,"  retorted 
McAndrew. 

"A  very  important  point  in  connection  with  pumping  out 
bilges  is  to  see  that  the  strainers  are  cleared.  The  bilges  of  all 
ships,  as  you  may  know,  usually  contain  ashes,  chunks  of  waste, 
shavings  and  other  refuse,  and  they  have  been  known  to  con- 
tain a  fireman's  undershirt  or  overalls.  These  things  if  drawn 
into  the  bilge  suction  pipes  would  soon  choke  them  up  and  the 
pumps  would  be  useless.  Hence  it  is  that  the  end  of  every 
pipe  is  fitted  with  some  form  of  a  perforated  strainer  to  catch 
the  refuse  before  it  can  get  into  the  pipes.  The  ordinary  form 
is  known  as  the  box  strainer,  which,  as  its  name  indicates,  is 
shaped  like  a  box,  and  has  all  its  sides  and  its  bottom  per- 
forated with  three-eighths  or  one-half  inch  holes.  The  top  of 
the  box  is  made  easily  removable  so  that  it  can  be  cleaned  out. 


PIPES    AND   VALVES 


143 


Unless  given  attention  frequently  these  strainers  themselves 
become  plugged  up  with  dirt  and  refuse,  and  you  young  men 
will  probably  never  appreciate  the  importance  of  keeping  them 
cleaned  out  until  you  are  called  on  some  night  while  the  ship 
is  rolling  and  pitching  in  a  gale  of  wind  to  dive  down  in  bilge 
water  up  to  your  armpits  for  the  purpose  of  digging  bunches 
of  waste  and  handfuls  of  ashes  out  of  the  strainer  boxes.  An 
old-time  chief  engineer  in  the  navy  conferred  a  lasting  boon 
on  seafaring  men  by  inventing  what  is  known  as  the  'Macomb 
strainer,'  a  device  whereby  the  water  is  strained  through  a 
metal  basket  in  a  cast  iron  body  with  a  removable  top.  By 
simply  removing  a  clamp  in  the  top  of  the  strainer  body  the 
basket  can  be  lifted  out  and  emptied  in  two  minutes.  This  in- 
vention has  saved  much  profanity  on  shipboard,  and  probably 
many  ships. 

"In  line  with  a  talk  on  piping,  and  incidentally  with  pro- 
fanity-provoking devices,  we  might  stop  casually  and  consider 
the  steam  trap,  a  necessary  evil  fitted  to  all  steam  plants.  The 
primary  purpose  of  a  steam  trap  is  to  separate  the  water  from 
steam  in  the  numerous  drains  with  which  all  marine  machinery 
must  be  fitted.  This  is  accomplished,  or,  I  might  add,  is  tried, 
to  be  accomplished,  in  two  principal  ways :  one  by  the  auto- 
matic filling  and  emptying  of  buckets  floating  in  the  water 
of  condensation,  and  the  other  by  difference  of  expansion  in 
metals  as  affected  by  the  variance  in  the  temperatures  of  steam 
and  water.  There  are  about  as  many  different  styles  of  steam 
traps  as  there  are  applicants  for  an  easy  job,  but  there  are  not 
more  than  two  or  three  of  these  styles  fit  to  use  on  board  ship. 
I  hesitate  to  tell  you  which  they  are,  as  I  am  a  little  uncertain 
even  about  their  efficiency  at  all  times. 

"Of  equal  importance  to  the  piping  on  board  ship  are  the 
valves  which  control  the  flow  of  steam  and  water  through 
them.  Most  of  the  work  of  the  engineer,  while  the  vessel  is 
under  way,  is  devoted  to  the  opening,  closing  and  regulating 


144 


MC  ANDREWS    FLOATING    SCHOOL 


of  valves.  Knowing  how  and  when  to  perform  these  functions 
constitutes  a  large  part  of  an  engineer's  practical  knowledge. 
The  efficient  working  of  marine  machinery  is  largely  dependent 
upon  the  proper  manipulation  of  valves,  and  on  the  other  hand 
nine-tenths  of  all  the  trouble  on  board  ship  is  occasioned  by 
the  wrong  manipulation  of  these  important  details.  With  this 


FIG.    26. GLOBE    VALVE 


introduction  to  the  subject  you  can  readily  see  that  it  will  be 
well  to  pay  a  little  attention  to  them.  The  valves  used  on  ship- 
board may  be  divided  into  principal  classes — angle  and  globe, 
stop  and  check,  and  gate  valves,  and  various  combinations  of 
these  types. 

"A  globe  valve  may  be  denned  as  one  in  which  the  steam, 
water,  etc.,  enters  and  leaves  the  valve  flowing  in  the  same 
direction;  an  angle  valve  is  one  in  which  the  steam,  water,  etc., 
enters  the  valve  flowing  in  one  direction  and  leaves  the  valve 


PIPES    AND   VALVES 


I4S 


flowing  in  a  direction  usually  at  right  angles  to  that  in  which 
it  enters.    Figs.  26  and  27  will  illustrate  these  two  types. 

"A  stop  valve  is  one  in  which  the  disk  is  under  absolute 
control  of  the  hand  wheel,  and  permits  of  flow  through  it  in 
either  direction. 


FIG.     27. ANGLE    STOP    VALVE 

"A  check  valve  is  one  in  which  the  stem  is  not  connected 
with  the  disk,  and  permits  of  flow  through  it  in  only  one 
direction.  It  can,  however,  be  shut  off  by  screwing  down  on 
the  hand  wheel. 

"A  gate  valve  is  one  in  which  the  disk  or  gate  is  set  at  right 
angles  to  the  direction  of  flow,  and  is  at  all  times  under  control 
of  the  hand  wheel.  (See  Fig.  28.) 

"A  cock  is  in  reality  a  valve  of  the  simplest  design,  wherein 
a  conical  plug  is  fitted  in  the  body,  and  the  flow  of  steam  or 
water  through  it  is  regulated  accordingly  as  the  slit  through 


146 


MC  ANDREW  S   FLOATING    SCHOOL 


the  plug  is  placed  in  line  with  the  direction  of  the  flow  or  at 
right  angles  to  it. 

"Valves  of  all  descriptions  are  made  principally  of  the  best 
quality  of  cast  iron,  as  that  is  the  cheapest  and  best  adapted 
metal  for  the  purpose.  Composition  is  frequently  used  for 
small  valves  and  for  larger  valves  in  high-class  work,  on  ac- 


SECTIONAL  ELEVATION 

FIG.     28. GATE    VALVE 


SECTIONAL  PLAN 
SHOWING  BY-PASS 


count  of  its  freedom  from  corrosion  and  greater  strength.  Its 
increased  cost,  however,  precludes  its  extensive  use. 

"Cast  steel  is  used  to  some  extent  for  valves  subjected  to 
very  high  steam  pressures,  owing  to  its  great  tensile  strength, 
but  the  difficulty  of  obtaining  good  castings,  free  from  blow- 
holes, limits  its  use  to  places  where  the  greater  strength  is 
absolutely  necessary. 

"It  is  usual  to  have  all  cast  iron  valves  'brass  mounted'; 
that  is,  to  fit  them  with  composition  seats,  disks,  stems  and 


PIPES   AND  VALVES  147. 

stuffing-boxes,  as  these  are  the  parts  subjected  to  the  greatest 
wear. 

"Seats  of  valves  become  grooved  by  the  constant  flow  of 
steam  or  water,  and  if  not  attended  to  regularly  are  bound 
to  leak.  Therefore  one  of  the  frequent  duties  of  an  engineer  is 
to  'grind  in'  leaky  valves,  an  operation  which  consists  of  re- 
moving the  valve  covers,  covering  the  seats  with  a  ground- 
glass  paste  and  revolving  the  disk  in  place  until  all  grooves  are 
removed.  A  valve  reseating  machine  is  a  device  for  'grinding 
in'  valves  mechanically  while  in  place,  the  same  as  it  would  be 
done  if  the  valve  was  removed  and  placed  in  a  lathe.  Such  a 
device  is  a  necessity  in  order  to  keep  valves  on  a  modern  ship 
always  tight." 

"Chief,  what  is  a  reducing  valve  used  for?"  interrupted 
Pierce. 

"Reducing  valves  are  of  comparatively  recent  use  around 
steam  plants,  and  have  been  made  a  necessity  by  the  constantly 
increasing  steam  pressures  now  being  used  on  board  ship. 
While  these  high  pressures  are  necessary  for  multiple-cylinder 
main  engines  to  increase  the  economy  of  working,  there  are 
still  certain  auxiliaries  on  all  ships  which  use  lower  steam 
pressures.  Among  these  may  be  mentioned  the  ordinary  recip- 
rocating dynamo  engines,  the  steering  engine,  the  windlass 
engine,  the  bilge  pumps,  the  heating  apparatus,  steam  jackets, 
etc.,  and,  in  fact,  wherever  it  is  desirable  to  have  low-pressure 
steam  at  a  uniform  pressure.  These  are  devices  whereby  the 
high-pressure  steam  from  the  boilers  may  be  reduced  and 
delivered  at  almost  any  pressure  desirable  by  regulating  the 
reducer,  after  which,  no  matter  how  much  the  boiler  pressure 
may  fluctuate,  a  steady  lower  pressure  is  maintained  for  the 
auxiliaries." 

"What  is  a  relief  valve,  and  why  are  they  fitted  on  some 
pumps?"  inquired  Schmidt. 

"A   relief    valve    is    simply   a    small    safety    valve,"    replied 


148  MC  ANDREW'S  FLOATING  SCHOOL 

McAndrew.  "I  have  already  told  you  why  these  are  useful 
on  the  main  engines.  On  some  pumps,  and  especially  fire 
pumps,  it  frequently  happens  that  a  careless  oiler  or  machinist 
will  start  the  pump  full  speed,  and  if  there  are  not  sufficient 
openings  of  the  stop  valves  along  the  fire  mains  the  pressure 
might  rupture  the  pipe.  For  that  reason  one  or  more  relief 
'  safety  valves,  set  to  blow  off  at  a  safe  pressure,  are  fitted  in  the 
fire  main,  usually  in  the  engine  room,  where  the  escaping  water 
can  do  no  particular  harm. 

"I  have  already  explained  to  you  that  a  valve  need  only  be 
opened  a  vertical  distance  equal  to  one-fourth  its  diameter, 
and  I  hope  you  will  bear  that  fact  in  mind.  Remember,  also, 
what  I  told  you  about  not  opening  a  steam  valve  quickly. 
That,  however,  does  not  apply  to  water  valves,  as  they  should 
be  opened  as  quickly  as  possible. 

"In  closing  this  lecture  I  will  call  your  attention  to  the  pipe 
covering.  In  general  all  pipes  transmitting  either  steam  or  hot 
water  should  be  covered  with  non-conducting  material,  such  as 
hair-felt  for  low  pressures,  and  magnesia  or  asbestos,  or  the 
various  components  of  each  for  the  higher  temperatures.  Es- 
caping heat  not  only  lowers  the  efficiency  of  any  steam  engine, 
but  it  adds  to  the  discomfiture  of  the  men  who  have  to  operate 
the  machinery.  If  you  ever  have  to  do  any  pipe  covering 
remember  that  you  should  not  cover  any  of  the  joints,  as  it  is 
often  necessary  to  get  at  them  quickly  to  make  new  joints,  or 
to  set  up  on  them  when  they  leak.  All  pipe  covering  should 
be  encased  in  canvas,  and  it  should  be  sewed  on  instead  of 
being  pasted,  as  some  contractors  like  to  do. 

"We  have  about  covered  in  a  general  way  all  parts  of  a 
marine  installation,  and  from  now  on  I  will  direct  your  atten- 
tion to  what  may  be  termed  specialties,  and  go  into  a  number 
of  subjects  with  which  you  will  have  to  be  familiar  before 
getting  your  ticket." 


CHAPTER  XVII 

Indicator  Cards  and  Horsepower 

"My  subject  this  evening  will  be  indicating  cards,"  re- 
marked McAndrew,  as  his  class  gathered  in  the  improvised 
school  room  after  a  hard  day's  work  in  connection  with  low- 
ering two  of  the  new  boilers  of  the  Tuscarora  in  place. 

"Do  you  know  what  a  steam  engine  indicator  is?"  he  in- 
quired, looking  at  O'Rourke,  who  he  surmised  would  be  the 
first  to  give  a  reply.  He  was  not  disappointed,  as  that  young 
man  immediately  volunteered  the  information  that  "an  indi- 
cator, sir,  is  a  nickel-plated  machine  that  looks  something  like 
a  pickle  castor ;  you  screw  it  into  the  outside  of  a  cylinder,  tie 
a  string  to  its  tail,  let  it  sneeze  three  or  four  times,  then  un- 
wrap a  piece  of  paper  from  the  outside,  which  you  carry  up  to 
the  chief  engineer,  who  looks  wise,  fixes  his  'specs,'  and  de- 
livers the  opinion  that  she's  got  too  much  compression,  what- 
ever that  is." 

"That's  a  fine  description,  O'Rourke,  and  shows  that  you  are 
a  man  of  keen  perception,  especially  as  to  the  'look  wise'  part 
of  the  performance.  The  appearance  of  knowing  all  about  it 
seems  to  attach  itself  to  the  face  of  every  man  who  has  an 
indicator  card  handed  to  him  for  inspection.  As  a  matter  of 
fact  there  are  a  great  many  people  who  look  at  indicator  cards 
in  this  manner  who  don't  know  much  more  about  them  than 
any  of  you  boys  do  right  now.  For  that  reason  I  intend  to 
tell  you  something  about  them,  so  that  you  will  not  altogether 
belie  your  looks  when  you  come  to  do  the  'wise'  act. 

"An  indicator,  as  its  name  implies,  is  used  to  indicate  what 


150  MC  ANDREW'S  FLOATING  SCHOOL 

transpires  inside  the  cylinder.  You  all  know  that  steam 
enters  at  one  end  of  the  engine  and  leaves  at  the  other;  but 
it  is  what  it  does  in  the  meantime  which  interests  us  most. 

"One  of  the  principal  features  of  the  indicator  is  a  small 
steam  cylinder,  which  can  be  connected  directly  to  either  one 
end  of  the  main  cylinder  or  the  other,  at  will,  by  simply  turning 
a  three-way  cock.  The  steam  acting  on  the  piston  in  this  small 
cylinder  is  therefore  duplicating  exactly  its  effect  on  the  piston 
of  the  cylinder  to  which  it  is  attached  at  every  portion  of  its 
stroke.  The  up  and  down  motion  of  this  small  piston  is  trans- 
mitted by  means  of  a  system  of  small  levers  and  links  to  a 
small  pencil  point,  which  is  made  to  move  in  a  straight  vertical 
line. 

"The  other  main  portion  of  the  indicator  is  the  barrel,  which 
by  means  of  a  cord  attached  to  a  specially  arranged  reducing 
gear,  is  given  a  rotary  motion  corresponding  on  a  small  scale, 
of  course,  to  the  simultaneous  action  of  the  steam  engine  piston. 
Then,  by  pressing  this  pencil  point,  moving  always  in  a  vertical 
line,  against  a  piece  of  paper  wrapped  around  the  rotating 
drum,  a  figure  is  drawn,  which,  to  the  initiated,  shows  ex- 
actly what  pressure  in  pounds  per  square  inch  is  being  ex- 
erted on  the  engine  piston  at  every  point  in  its  stroke. 

"The  little  piston  works  against  a  spiral  spring  of  a  tension 
designed  according  to  the  pressure  which  is  expected  to  be 
used  in  the  cylinder.  On  the  high-pressure  cylinder  we  would 
use  springs  of  from  60  to  100  pounds  tension,  on  the  inter- 
mediate from  20  to  50  pounds,  and  on  the  low-pressure  a  spring 
of  about  10  pounds  tension." 

Here  McAndrew  drew  the  sketch  (Fig.  29)  on  the  black- 
board, and  said,  "This  represents  an  ideal  indicator  card  taken 
from  a  single-cylinder  condensing  engine." 

"Huh  !"  remarked  O'Rourke,  after  the  sketch  had  been  com- 
pleted, "that  looks  like  one  of  those  wooden  shoes  that 
Schmidt's  grandfather  wore." 


INDICATOR   CARDS   AND    HORSEPOWER  151 

Schmidt  retaliated  by  remarking  that  he  would  bet  that 
O'Rourke's  grandfather  was  a  bog-trotter,  and  didn't  have 
shoes  of  any  kind  to  wear. 

"That'll  do,"  suggested  McAndrew.  "This  is  no  lecture  on 
'Shoes  of  All  Nations.' 

"This  card  is  what  you  would  get  off  a  well-designed  engine. 
The  line  PQ  is  known  as  the  atmospheric  line,  or  the  line 


FIG.     29. INDICATOR    CARD 

showing  the  pressure  of  the  atmosphere.  It  should  always  be 
drawn  on  the  card  before  making  the  connection  to  either  end 
of  the  cylinder,  or  otherwise  your  card  will  not  be  of  much 
value.  The  line  RS  is  known  as  the  line  of  zero  pressure,  and 
has  to  be  drawn  on  the  card  with  a  ruler.  As  the  pressure  of 
the  atmosphere  is,  as  I  have  told  you  before,  14.7  pounds  per 
square  inch,  it  should  be  a  distance  below  the  atmospheric  line 
equivalent  to  that  pressure  on  the  scale  used  for  whichever 
tension  of  spring  has  been  used  in  the  indicator.  For  example, 
if  a  3O-pound  spring  has  been  used,  the  zero  line  would  be 
about  one-half  inch  below  the  atmospheric  line  and  always 
parallel  to  it." 

"What's  parallel  mean?"  whispered  O'Rourke  to  Pierce. 

Overhearing  the  question,  McAndrew  said,  "I  am  surprised 
that  you  don't  know  the  meaning  of  that  term.  'Parallel' 
means  two  lines  that  are  the  same  distance  apart  at  all  points, 


152  MC  ANDREW'S  FLOATING  SCHOOL 

like  railroad  tracks,  for  instance ;  they  never  meet  no  matter 
how  far  they  are  extended." 

"Schmidt's  feet  must  be  parallel,  then,"  interjected 
O'Rourke.  "He'  so  bow-legged  that  they  have  never  met  yet.'' 

"Now  referring  to  the  figure  again,"  McAndrew  continued, 
"you  all  know  that  the  steam  is  admitted  to  the  cylinder  at 
the  end  of  each  stroke  almost  instantaneously  as  the  valve 
opens;  this  causes  the  pencil  point  to  go  up  almost  vertically 
as  the  revolving  drum,  following  the  motion  of  the  engine 
piston,  is  then  practically  at  a  standstill  while  changing  di- 
rection. This  line  AF  on  the  card  is  known  as  the  admission 
line ;  as  the  valve  remains  open  the  steam  continues  to  rush  in 
at  the  same  pressure,  thus  making  the  line  AB  practically 
parallel  to  the  atmospheric  line.  This  line  AB  is  known  as  the 
steam  line.  B  is  the  point  of  cut-off,  where  steam  can  no 
longer  enter  the  cylinder  direct  from  the  boilers.  The  point  of 
cut-off  varies  from  .3  to  .7  of  the  stroke,  according  to  the 
various  conditions. 

"After  the  valve  closes,  the  steam  in  the  cylinder  continues 
to  shove  the  piston  on  its  travel  by  the  expansive  force  of  the 
steam.  As  the  piston  proceeds  on  its  stroke  the  pressure  of  the 
steam  gradually  drops,  so  that  the  line  traced  by  the  pencil 
assumes  a  curved  shape  as  shown  in  the  diagram ;  this  line  BD 
is  known  as  the  expansion  line.  At  the  point  D  the  valve 
opens  to  the  exhaust,  and  the  steam  rushes  out  of  the  cylinder." 

"Do  they  call  it  'exhausted'  because  the  steam  is  tired  out 
from  pushing  the  piston?"  inquired  O'Rourke. 

"Very  likely  that's  the  reason,"  smilingly  replied  McAn- 
drew. 

"The  live  steam  is  now  being  admitted  to  the  other  end  of 
the  cylinder  driving  the  piston  on  its  return  stroke,  and  the 
expanded  steam,  or  'tired'  steam,  as  O'Rourke  thinks  it  is, 
continues  to  escape  from  the  opposite  end  until  suddenly  the 
valve  closes  at  the  point  E  in  the  stroke,  and  a  certain  amount 


INDICATOR   CARDS   AND    HORSEPOWER  153 

of  this  'tired'  steam  is  imprisoned  in  the  cylinder.  As  the 
piston  has  not  yet  finished  its  stroke  this  portion  of  the  ex- 
haust steam  is  compresed  in  the  cylinder,  and  acts  as  a  spring 
to  overcome  the  momentum  of  the  piston  when  it  reaches  the 
end  of  the  stroke.  It  thus  acts  very  much  like  a  bumper  on  a 
freight  car.  At  the  point  F  live  steam  is  again  admitted  to 
that  end  of  the  cylinder,  and  the  operation,  which  I  have  out- 
lined, is  repeated. 

"The  card  which  I  have  shown  you  is,  of  course,  for  only 
one  end  of  the  cylinder ;  the  card  from  the  other  end  will  be 
of  the  same  general  shape,  and  the  pair  will  look  like  Fig.  30" : 


FIG.     30. PAIR     OF    INDICATOR     CARDS 

"That  looks  like  a  pair  of  wooden  shoes  on  a  pigeon-toed 

man." 

"What  good  are  all  these  indicator  cards?"  inquired  Nelson. 

"That's  the  point  I  am  coming  to,"  replied  McAndrew. 
"They  are  not  of  any  use  unless  you  can  read  them  intelli- 
gently. An  indicator  card  to  a  trained  engineer  serves  about 
the  same  purpose  as  counting  the  pulse,  taking  the  temperature 
and  looking  at  the  tongue  of  a  sick  man  does  to  a  physician. 
You  find  out  what  is  going  on  inside.  If  there  is  anything 
wrong  with  the  valves,  or  if  the  piston  is  leaking,  it  is  shown 
at  once  on  the  card.  The  principal  value  of  a  card  is,  however, 
to  tell  how  much  power  is  being  developed  by  the  engine,  and 
how  it  is  distributed  among  the  cylinders  of  a  multiple-expan- 
sion engine. 


154  MC  ANDREWS    FLOATING    SCHOOL 

"Here  are  some  of  the  examples  of  wrong  valve  setting 
which  can  be  detected. 

"All  eccentrics  of  a  Stephenson  link  motion  valve  gear,  the 
one  most  universally  used  in  marine  work,  are  set  at  right 
angles,  or  one-fourth  of  the  circumference  of  the  crank  circle 
in  advance  of  the  crank,  plus  a  small  angle  known  as  the 
angular  advance.  Now  if  this  angular  advance  is  too  large, 
cut-off  occurs  too  soon,  the  steam  lead,  or  time  the  valve  is 
open  before  the  piston  reaches  the  end  of  the  stroke,  is  too 
great,  and  the  opening  and  closing  of  the  exhaust  occur  too 
soon ;  in  other  words,  all  of  the  functions  of  the  valve  are 
ahead  of  time,  and  the  result  is  shown  by  a  card  such  as  I 
have  shown  in  Fig.  31. 

"If,  on  the  contrary,  this  angular  advance  is  too  small,  then 
all  of  the  functions  of  the  valve  are  too  late,  and  the  resulting 
card  will  be  like  Fig.  32. 


FIG.      31. INDICATOR     CARDS,     WITH     ANGULAR     ADVANCE    TOO    LARGE 

"The  steam  lap  of  a  valve  is,  as  you  have  been  told  before, 
the  amount  the  valve  laps  over  the  steam  port  when  the  valve 
is  in  its  mid-position;  the  general  effect  of  such  a  condition 
is  that  the  cut-off  is  too  soon,  the  steam  opening  is  late,  and  as 
there  is  not  sufficient  opening  for  the  entrance  of  the  steam, 
there  is  a  certain  amount  of  wire-drawing  or  the  effect  of 
passing  steam  through  a  contracted  opening.  This  is  also  in- 
dicated by  a  drop  in  the  pressure,  which  makes  the  steam  line 


INDICATOR  CARDS   AND   HORSEPOWER 


155 


get  away  from  its  parallel  position  to   the  atmospheric  line. 
Such  a  state  of  affairs  produces  a  card  like  Fig.  33. 

"The  opposite  effect  is  caused  in  all  the  functions  of  the 
valve  if  the  steam  lap  is  too  small,  as  shown  by  a  card  like 
Fig.  34- 


FIG.     32. INDICATOR    CARD,    WITH    ANGULAR    ADVANCE    TOO    SMALL 


FIG.     33. INDICATOR    CARD,     WITH     STEAM     LAP    TOO    LARGE 


FIG.      34. INDICATOR     CARD,     WITH      STEAM     LAP     TOO     SMALL 

"In  the  layout  of  the  valve  gear  the  designer  may  have 
made  the  valve  stem  too  long;  this  would  result  in  too  much 
steam  lap  on  top  and  too  little  exhaust  lap  on  the  bottom, 
which  would  make  the  cut-off  too  early  at  the  top  and  too 
late  at  the  bottom,  the  steam  opening  on  top  late  and  at  the 
bottom  too  early.  Such  a  contingency  would  produce  a  card 
like  Fig.  35." 


156  MC  ANDREW'S  FLOATING  SCHOOL 

"That  looks  as  if  somebody  had  given  it  a  swift  kick,"  said 
O'Rourke. 

"Exactly  so,"  replied  McAndrew.  "And  if  the  valve  stem 
was  too  short  it  would  look  as  if  it  had  received  a  swift  kick 
at  the  other  end. 

"Now  if  the  piston  was  leaking  badly  the  result  would  be 
very  noticeable  on  the  expansion  line,  as  it  would  not  be  so  full 
as  it  is  when  the  piston  is  tight  and  the  steam  is  expanded 
normally.  In  other  words  the  expansion  line  would  drop  below 


FIG.    35. INDICATOR    CARD,    WITH    VALVE   STEM    TOO    LONG   OR    TOO    SHORT 

its  right  position  on  the  card,  showing  that  the  pressure  was 
low  on  account  of  the  leak. 

"There  are  many  other  conditions  that  are  shown  by  the 
shape  of  the  indicator  cards,  most  of  which  can  be  reasoned 
out  by  understanding  the  general  conditions  affecting  the 
steam  in  the  cylinder.  As  your  experience  in  reading  indicator 
cards  progresses  you  will  be  better  able  to  interpret  the  con- 
ditions which  exist. 

"We  now  come  to  the  calculation  of  horsepower  from  the 
indicator  diagrams.  You  will  remember  that  in  the  early  days 
of  this  Floating  School  I  tried  to  impress  upon  you  the  mean- 
ing of  power;  that  is,  that  it  consists  of  three  elements — force, 
in  pounds ;  distance,  in  feet ;  and  time,  in  minutes. 

"The  element  of  distance  is  quite  easily  determined,  as 
knowing  the  stroke  of  the  engine  in  inches,  we  can,  by  counting 
the  revolutions  and  multiplying  that  number  by  two  (as  it 


INDICATOR  CARDS  AND  HORSEPOWER 


157 


takes  two  strokes  to  make  a  revolution),  quite  easily  deter' 
mine  how  far  the  piston  has  traveled  in  any  given  time. 

"The  element  of  time  is  readily  determined  by  observations 
on  the  engine-room  clock  or  on  a  watch  held  in  the  hand. 

"The  third  element,  of  force  exerted  in  pounds,  is  more 
difficult  to  determine,  and  is  the  only  essential  in  the  calcula- 
tion which  is  furnished  by  means  of  the  indicator  card.  We 
know  that  the  steam  enters  a  cylinder  at  a  little  less  pressure 
than  shown  by  the  boiler  gage,  and  that  it  leaves  at  a  greatly 


1   4242424241 


reduced  pressure.  When  we  have  different  pressures  at  every 
point  of  the  piston's  travel,  in  order  to  determine  the  total 
pressure  exerted  we  must  take  the  average  of  all  the  pressures. 
This  is  where  the  indicator  card  comes  into  use,  as  from  the 
scale  of  the  spring  used  it  is  possible  to  determine  the  pressure 
exerted  at  every  point  of  the  stroke.  To  get  the  average 
pressure  from  an  indicator  card  the  simplest  method  is  as 
follows : 

"Divide  the  card  into  ten  intervals,  as  shown  by  y0,  y-i,  etc. 
Between  each  of  these  spaces  draw  dotted  lines  just  half-way 
between  the  full  lines.  Now  add  up  the  lengths  of  all  these 
ten  lines,  either  by  measuring  each  one  separately  or  trans- 


1.58  MC  ANDREW'S  FLOATING  SCHOOL 

ferring  them  one  after  another  to  a  strip  of  paper;  divide 
the  total  length  of  all  these  dotted  lines  by  10,  and  the  answer, 
multiplied  by  the  scale  of  the  spring,  will  give  you  the  average 
pressure  exerted  on  the  piston. 

"Another  method  is  by  what  is  known  as  a  planimeter,  a 
small  instrument  which  usually  comes  with  every  set  of  in- 
dicators. By  this  instrument  we  can  ascertain  the  area  of  any 
irregular  figure.  We  can  easily  measure  the  length  of  the 
card,  so  by  dividing  the  area  in  square  inches  by  the  length 
in  inches,  the  quotient  will  give  us  the  average  height,  also  in 
inches.  This  height,  multiplied  by  the  scale  of  the  spring, 
gives  the  mean  or  average  pressure. 

"Having  ascertained  the  mean  pressure  per  square  inch,  the 
next  step  is  to  find  out  the  total  pressure  on  the  piston.  The 
rule  for  the  area  of  any  circle  is  to  square  the  diameter;  that 
is,  multiply  it  by  itself,  and  then  multiply  that  quotient  by  the 
figures  .7854,  which  gives  the  area  in  square  inches.  Knowing 
the  pressure  per  square  inch  and  the  total  number  of  square 
inches  in  the  piston,  we  multiply  them  together  to  find  the  total 
pressure  in  pounds  on  the  whole  piston,  which  is,  as  I  told 
you,  the  last  of  the  three  elements  necessary  in  calculating 
horsepower." 

"What  has  'drawing'  got  to  do  with  figuring  horsepower?" 
inquired  O'Rourke. 

"I  don't  quite  understand  you,"  said  McAndrew. 

"A  guy  out  here  in  the  shipyard  told  me  only  this  morning 
that  all  you  had  to  do  was  to  remember  the  word  'drawing' 
and  you  could  figure  horsepower,"  argued  O'Rourke. 

"Oh!  I  see  what  you  are  driving  at.  You  mean  the  word 
P-L-A-N,  not  drawing.  That  word  has  been  connected  with 
the  subject  ever  since  horsepower  was  invented.  It  is  a  good 
way  to  remember  the  calculation,  providing  you  know  what 
the  letters  signify. 


INDICATOR  CARDS  AND  HORSEPOWER  159 

P  means  the  average  pressure  per  square  inch ;  L  stands  for 
the  length  of  stroke;  A  is  the  area  of  the  piston;  N  is  the 
number  of  revolutions. 

"It  is  much  better  to  remember  the  method,  however,  by 
reasoning  the  matter  out  in  terms  of  force,  distance  and  time, 
as  I  have  already  told  you.  We  want  to  get  the  whole  problem 
into  so  many  foot  pounds  per  minute,  then  we  know  that 
dividing  by  33,000  will  give  us  the  horsepower.  The  best  way 
to  illustrate  the  method  is  to  work  out  a  specimen  for  you. 
For  example: 

"A  certain  steam  cylinder  is  41  inches  in  diameter,  the  stroke 
is  36  inches,  the  mean  effective  pressure  is  42  pounds  per 
square  inch,  and  the  number  of  revolutions  is  no  per  minute. 
What  is  the  horsepower? 

"We  find  the  area  of  the  piston  as  follows : 


164 


1681 
7854 

6724 
8405 
13448 
11767 

1320.2574 

"Now  multiply  the  area  by  the  mean  effective  pressure, 
1320.25 

42 


264050 
528100 

55450.50 


160  MC  ANDREW'S  FLOATING  SCHOOL 

"This  gives  us  the  total  pounds  pressure  exerted  on  the 
piston  and  is  the  element  of  force. 

"The  distance  the  piston  moves  through  is,  of  course,  equal 
to  twice  the  stroke,  as  the  piston  has  to  go  up  and  down  to 
make  one  revolution,  therefore  as  36  inches  are  equal  to  3  feet, 
multiply  by  2,  and  we  have  6  feet  as  the  distance  moved  in  one 
revolution,  and  in  no  revolutions  it  will  have  moved  660  feet — 
this  is  the  element  of  distance. 

"The  element  of  time  is,  of  course,  one  minute,  as  that  is 
the  basis  on  which  horsepower  is  taken. 

"Now  multiply  the  force  (5545O-5  pounds)  by  the  distance 
(660  feet),  and  we  get  36,597>33O  foot  pounds  per  minute.  Di- 
viding this  number  by  33,000  we  find  the  answer  to  be  1109 
horsepower.  The  calculations  I  have  shown  you  would  be  all 
right  if  there  were  no  piston  rod ;  but  as  that  is,  of  course,  a 
necessity,  we  must  make  allowances  for  the  area  of  the  rod,  as 
no  pressure  is  exerted  on  that  portion  of  the  piston  occupied  by 
the  rod.  I  should  also  tell  you  that  in  making  the  calculations 
the  mean  effective  pressure  per  square  inch  must  be  taken  as 
the  average  obtained  from  the  top  and  bottom  indicator  cards. 

"To  allow  for  the  piston  rod  it  is  customary  to  calculate  its 
area  the  same  as  for  any  other  circle,  and  to  take  only  half  the 
area  of  the  rod  from  the  total  area  of  the  piston,  as  the  rod  is, 
as  you  know,  on  only  one  side.  Thus  the  area  of  a  piston  rod 
6  inches  in  diameter  is  28.274  square  inches.  One-half  of  that 
is  14.137  square  inches.  This  should  be  subtracted  from  the 
total  area  of  the  piston  1320.25,  which  would  leave  1306.11 
square  inches  to  be  multiplied  by  42  to  obtain  the  element 
force,  average  or  total  pressure  on  the  piston." 

"Chief,  what's  the  use  of  all  this  'dope'  about  indicator  cards 
and  horsepower  to  the  men  that  drive  the  engine?"  asked 
Pierce. 

"I  don't  suppose  that  it  is  very  valuable  to  the  ordinary  every- 
day engine-driving  man  on  board  ship,  but  engineers  are  some- 


INDICATOR  CARDS  AND   HORSEPOWER  l6l 

what  like  lawyers  in  this  respect.  Every  lawyer  likes  to  study 
about  the  Constitution  and  be  admitted  to  practice  before  the 
Supreme  Court.  About  one  in  every  hundred  ever  has  oc- 
casion to  use  his  knowledge  in  that  connection,  but  he  would 
be  a  poor  lawyer  if  he  didn't  aim  that  high." 


CHAPTER  XVIII 
Care  and  Management  of  Boilers 

For  several  weeks  there  had  been  an  enforced  vacation  in 
the  Floating  School,  the  reason  being  that  the  work  of  in- 
stalling the  new  boilers  on  the  Tuscarora  had  been  rushed 
night  and  day  in  order  to  get  the  ship  out  in  time  for  the  heavy 
trade  in  the  autumn  months.  The  members  of  the  school  had 
been  kept  so  busy  that  they  had  but  little  time  for  study,  and 
Chief  McAndrew,  of  course,  had  so  much  to  attend  to  in  the 
thousand  and  one  details  a  chief  engineer  has  to  think  of  that 
he  had  no  opportunity  to  give  the  young  men  any  attention. 
The  repair  work  was  finally  declared  completed ;  a  dock  trial 
had  been  held  and  the  new  boilers  found  satisfactory.  The 
ship  was  to  sail  early  the  next  morning;  O'Rourke  and 
Schmidt  had  been  given  two  hours'  liberty,  in  which  time  they 
had  taken  a  fond  farewell  of  their  Fishtown  girls.  Nelson  and 
Pierce  denied  that  they  had  any  particular  sweethearts  in 
Philadelphia,  but  they  had  enjoyed  their  stay  in  that  place  so 
much  that  they  were  somewhat  loath  to  leave. 

A  full  crew  had  been  shipped  for  the  engineer's  department, 
and  the  Chief  had  so  arranged  it  that  all  of  his  pupils  would 
be  in  one  watch.  Much  to  his  gratification,  Jim  Pierce  had 
been  promoted  to  be  an  oiler.  Gus  Schmidt  had  been  given  a 
boost  by  being  signed  as  a  water-tender,  which  led  O'Rourke 
to  remark  that  it  must  have  been  because  he  was  so  fond  of 
water.  Nelson  and  O'Rourke  were  still  retained  as  firemen, 
but  the  Chief  had  promised  them  that  if  they  paid  close  at- 
tention to  business  they  would  be  given  the  first  vacancies  as 
water-tenders. 

The  Chief,  of  course,  having  three  assistants,  stood  no  watch, 
and  he  very  kindly  agreed  to  continue  his  classes  at  such 


CARE  AND  MANAGEMENT  OF  BOILERS  163 

intervals  while  the  four  aspirants  for  licenses  were  "off  watch," 
as  it  might  be  convenient  for  him  to  spare  them  a  little  of  his 
time. 

The  ship  proceeded  down  the  Delaware  River  on  her  way  to 
New  York,  and  as  the  four  young  men  stood  the  8  to  12  watch, 
McAndrew  said  he  would  give  them  an  hour  or  so  of  his  time 
that  afternoon.  The  school  was  quite  a  mystery  to  the  other 
men  in  the  engineer's  crowd,  and  some  of  them  were  inclined 
to  be  a  little  facetious  about  the  four  "high  brows,"  as  they 
termed  them.  However,  as  information  regarding  the  school 
was  imparted  to  them  almost  simultaneously  with  an  exploita- 
tion of  the  fact  that  O'Rourke  had  been  awarded  several  prizes 
as  a  heavyweight  boxer  at  an  East  Side  resort,  the  tendency 
to  sarcastic  remarks  rapidly  dwindled. 

On  addressing  his  class  that  particular  afternoon,  McAndrew 
.  stated  that  as  the  ship  was  now  at  sea,  and  was  to  continue  on 
her  regular  duties,  he  would  take  up  the  subject  of  the  care 
and  management  of  machinery,  and  naturally  would  begin  at 
the  boilers. 

"Before  starting  fires  under  boilers,"  he  said,  "we  must  first 
examine  everything  connected  with  them.  See  that  all  stems 
on  the  stop  valves,  check  valves  and  blow  valves  are  oiled,  and 
that  the  valves  can  be  worked  freely.  The  safety  valve  gear 
should  be  put  in  good  working  condition,  and  the  valves  raised 
slightly  off  their  seats.  The  air  cock  at  the  top  of  the  boiler 
should  be  opened,  or  if  none  such  is  fitted,  open  the  top  gage- 
cock  in  order  to  allow  the  air  to  escape.  See  that  the  grate- 
bars  are  all  in  place,  that  the  damper  works  freely,  that  the 
handhole  and  manhole  plates  are  set  up  tight,  that  all  neces- 
sary fire  tools  are  on  hand,  that  the  bunker  doors  are  opened, 
and  that  the  surface  and  bottom  blow  valves  and  drain  cocks 
are  closed  tightly. 

"If  steam  has  not  been  raised  on  any  of  the  boilers  so  as  to 
allow  the  running  of  the  pumps,  the  boilers  should  be  filled  by 


164  MC  ANDREW'S  FLOATING  SCHOOL 

means  of  a  hose  from  the  deck,  through  the  top  manhole 
plates.  It  is  only  necessary  to  fill  the  boiler  up  to  about  two- 
thirds  of  a  glass,  as  the  water  'swells/  as  the  term  is,  when 
heat  is  applied  to  it.  That  is,  in  an  ordinary  boiler  the  water 
expands  in  volume  as  it  is  heated  until  it  rises  2  or  3  inches 
in  the  glass.  If  no  hot  coals  from  another  boiler  are  available, 
after  throwing  some  coal  on  the  bars,  it  is  usual  to  start  a 
wood  fire  at  first  and  throw  on  a  light  covering  of  coal  after 
the  fire  has  commenced  to  burn  freely.  Soft  coal  catches  fire 
comparatively  easily,  and  so  your  fires  will  soon  be  burning  in 
all  the  furnaces.  In  Scotch  boilers  great  care  must  be  taken 
not  to  force  the  fires  and  raise  steam  too  quickly.  It  takes 
a  long  time  to  get  the  heavy  shell  plates  warmed  through  uni- 
formly, and  if  steam  is  raised  too  hurriedly  the  seams  will 
begin  to  leak  on  account  of  the  unequal  expansion.  For  that 
reason  it  is  usual  to  take  from  six  to  twelve  hours'  time  in  • 
raising  steam.  One  of  the  great  advantages  of  watertube 
boilers  is  that  steam  can  be  raised  rapidly  without  doing  them 
any  harm,  as  from  their  construction  the  water  is  rapidly  cir- 
culated in  all  parts,  and  a  uniform  temperature  throughout  is 
easy  to  maintain.  For  that  reason  it  is  safe  to  raise  steam 
in  the  average  watertube  boilers  in  a  half  hour  if  deemed 
necessary. 

"The  great  disadvantage  of  all  Scotch  boilers  is  the  large 
amount  of  water  underneath  the  furnace  which  will  not  cir- 
culate naturally,  and  consequently  remains  quite  cool  even 
after  steam  is  formed.  To  overcome  this  there  are  several 
patented  devices  which  can  be  fitted  to  Scotch  boilers,  which 
will  automatically  circulate  the  dead  water  under  the  furnaces 
until  the  temperature  is  raised  to  very  near  that  of  the  water 
above  the  furnaces.  On  ships  which  are  not  provided  with 
such  apparatus  it  is  customary,  if  steam  is  available  from  an- 
other boiler,  to  run  the  auxiliary  feed  pump  slowly,  with  its 
suction  connected  to  the  bottom  blow,  and  its  discharge  enter- 


CARE  AND  MANAGEMENT  OF  BOILERS  16$ 

ing  the  boiler  through  the  regular  feed  pipe.  This  starts  up  a 
forced  circulation  and  greatly  facilitates  the  raising  of  steam. 

"As  steam  begins  to  form  slowly  it  will  be  first  indicated  by 
a  slight  hissing  noise  of  the  air  escaping  through  the  air-cock 
or  the  gage-cock.  This  air  should  be  allowed  to  blow  until 
clear  steam  can  be  seen  escaping.  Then  the  safety  valves 
should  be  lowered,  all  cocks  closed,  and  the  steam  pressure 
allowed  to  rise  slowly,  not  over  a  rate  of  ten  pounds  an  hour 
if  there  is  no  particular  hurry  about  the  operation.  When  the 
pressure  rises  to,  say,  100  pounds,  the  auxiliary  stop  valve 
should  be  opened  and  steam  admitted  to  the  auxiliary  line  for 
the  purpose  of  running  the  various  auxiliaries. 

"Having  raised  the  steam  to  the  working  pressure,  and  put 
the  boiler  in  service,  the  object  of  the  engineer  should  be  to 
keep  it  up  to  its  highest  state  of  efficiency;  that  is,  to  get  out 
the  most  steam  for  the  least  expenditure  of  coal.  To  do  this 
requires  constant  care  and  attention,  for,  like  human  beings, 
boilers  respond  readily  to  good  treatment  and  rebel  at  harsh 
treatment.  There  are  three  principal  things  to  do,  which,  if 
attended  to  Mitelligently,  will  keep  a  boiler  in  good  condition. 
The  first  of  these  is  to  feed  it  with  pure  water;  second,  do 
not  subject  it  to  sudden  changes  of  temperature,  and,  third, 
fire  it  properly. 

"If  these  three  maxims  were  lived  up  to  there  would  be  but 
little  trouble.  Unfortunately,  however,  they  are  difficult  of 
accomplishment,  and  for  that  reason  the  average  boiler  is  beset 
with  many  ills.  Most  of  these  arise  from  the  quality  of  the 
water  fed  to  the  steel  workman.  In  spite  of  precautions  grease 
will  get  in  the  feed  water  from  the  condensed  steam;  acids 
will  be  generated  by  the  contact  with  the  copper  condenser 
tubes  and  feed  pipes,  and  salt  water  will  get  in  through  leaks 
in  the  condenser  tubes  and  pipe  connections,  and  occasionally 
salt  water  will  have  to  be  fed  to  make  up  losses.  It  is  these 
foreign  elements  in  the  feed  water  which  make  all  the 
trouble." 


i66  MC  ANDREW'S  FLOATING  SCHOOL 

"Yes,"  broke  in  O'Rourke,  with  a  meaning  glare  at  Schmidt, 
"and  my  father  always  used  to  say  that  it  is  the  foreign  ele- 
ments that  make  all  the  trouble  in  this  country." 

"Is  that  so?"  sarcastically  replied  Schmidt.  "I'll  bet  it 
wasn't  many  days  before  you  were  born  that  he  was  tramping 
through  Castle  Garden  himself." 

"I  don't  suppose  that  any  of  us  is  eligible  to  join  the  Sons 
of  the  American  Revolution,"  said  McAndrew ;  "but  that  cuts 
no  figure  in  this  land  of  the  free. 

"As  I  was  saying  before  being  so  rudely  interrupted,  if  it 
were  not  for  the  impurities  which  get  into  the  boilers  the 
engineer  would  have  but  little  trouble  in  keeping  the  interior 
surfaces  clean.  To  counteract  all  these  impurities  is  one  of  the 
main  parts  of  an  engineer's  duty.  Hence  one  of  the  first 
things  to  do  is  to  ascertain  how  much  salt  water  slips  in  from 
one  source  or  another.  Since  steam  vessels  first  plied  the 
oceans,  every  one  has  been  fitted  with  an  instrument  known 
as  a  salinometer — not  'salometer,'  as  I  have  heard  O'Rourke 
term  it.  This  word  means  literally  salt  measure,  and  at  that  it 
does  not  express  its  use  correctly. 

"Salt,  of  course,  is  one  of  the  principal  solids  in  salt  water, 
but  there  are  enough  other  chemicals  in  it  to  start  a  small  drug 
store.  In  case  any  one  ever  asks  you  what  salt  water  does 
contain  you  can  refer  to  this  analysis  of  the  average  sea  water, 
as  it  contains  the  following  parts  in  1000 : 

Water  964745 

Chloride  of  sodium  (common  salt) 27.059 

Chloride  of  potassium  .766 

Chloride  of  magnesium 3.666 

Bromide  of  magnesium .029 

Sulphate  of  magnesia  (Epsom  salts) 2.296 

Sulphate  of  lime  (plaster  of  paris) 1.406 

Carbonate  of  lime  (chalk) .033 

1000.00 


CARE  AND    MANAGEMENT  OF  BOILERS  167 

"Some  chemists  state  that  there  is  also  a  small  quantity  of 
gold  in  sea  water;  but  I  wouldn't  advise  any  of  you  to  buy 
any  stock  in  a  company  formed  for  the  purpose  of  getting  gold 
from  that  source. 

"Although  the  instrument  I  have  referred  to  is  called  a  salt 
measure,  its  real  purpose  is  to  determine  how  much  solid 
matter  is  contained  in  the  water.  By  adding  up  the  amounts 
of  all  the  solid  ingredients  in  sea  water  you  will  see  that  they 
foot  up  approximately  1/32  of  the  entire  weight  of  the  water. 
That  is,  in  i  pound  of  salt  water  there  would  be  1/32  pound, 
or  y2  ounce,  of  solids.  Hence  all  salinometers  are  graded  on 
that  basis;  1/32  means  salt  water  as  drawn  from  the  sea;  2/32 
means  twice  as  much  solid  contents  as  ordinary  sea  water,  and 
so  on.  „ 

"With  every  salinometer  there  is  a  small  glass  instrument 
weighted  with  shot  known  as  a  hydrometer.  This  instrument 
is  usually  graduated  in  divisions  known  as  32nds,  which  is 
based  upon  the  principle  that  a  floating  body  displaces  an 
amount  of  water  equal  to  its  own  weight.  Hence  the  heavier 
or  denser  the  water  it  floats  in,  the  higher  will  be  the  portion 
out  of  the  water.  That  is  the  reason  that  it  is  easier  for  a  man 
to  float  in  salt  water  than  it  is  in  fresh  water.  I  have  told 
you  before  that  water  expands  when  heated,  hence  its  weight 
or  density  varies  with  its  temperature.  Therefore,  to  use 
the  hydrometer  correctly,  the  water  to  be  tested  must  be  at 
the  same  temperature  for  which  the  scale  on  the  hydrometer 
is  adjusted. 

"On  most  hydrometers  there  are  three  scales  shown — one 
at  190,  one  at  200  and  the  other  at  210  degrees  F.  The  method 
of  testing  is  to  open  the  cock  and  allow  the  boiler  water  to  fill 
a  brass  vessel,  known  as  the  salinometer  pot ;  if  it  is  below  190 
degrees  F.,  as  shown  by  the  thermometer,  admit  sufficient  hot 
water  from  the  boiler  to  heat  it  up  to  one  of  the  three  tempera- 
tures shown  on  the  scale.  Then  put  in  the  hydrometer  and 


i68  MC  ANDREW'S  FLOATING  SCHOOL 

observe  how  high  it  floats  on  the  temperature  scale  cor- 
responding to  the  temperature  of  the  water.  If  you  should 
hear  some  one  say  that  the  water  is  2*4  or  2^2,  it  would  mean 
2^4  thirty-seconds,  or  2^  thirty-seconds,  as  the  case  might  be. 

"I  have  devoted  some  time  to  telling  you  about  the  salino- 
meter  and  how  to  use  it,  but  I  will  tell  you  very  briefly  that  it 
is  not  of  much  value  nowadays,  as  that  method  is  too  crude 
for  modern  usage.  You  might  as  well  weigh  drugs  on  a  hay 
scale,  so  far  as  accuracy  is  concerned.  There  is  in  use  on  a 
number  of  ships  a  chemical  process  for  determining  accurately 
the  amounts  of  the  principal  ingredients  in  boiler  water;  the 
apparatus  is  so  simple  that  if  the  directions  are  closely  fol- 
lowed any  engineer  can  use  it. 

"Very  few  marine  engineers  allow  salt  water  to  be  used  for 
make-up  feed  in  these  days,  hence  it  is  not  so  essential  to 
guard  against  scale-forming  ingredients  in  the  water.  The 
principal  causes  of  deterioration,  such  as  rust  and  pitting,  are 
due  to  the  acids  which  get  into  the  boiler  water  and  thus 
encourage  galvanic  action." 

"What's  that?"  blurted  out  O'Rourke. 

"I  thought  you  wouldn't  understand  it,  O'Rourke,  and  so  I 
used  the  term  to  arouse  your  curiosity.  The  word  'galvanic' 
is  derived  from  the  name  Galvini,  an  Italian  scientist,  who 
first  discovered  that  an  electric  current  is  set  up  by  the  action 
of  one  metal  on  another.  You  all  probably  know  something 
about  the  ordinary  battery  used  for  generating  an  electric 
current.  This  consists  of  a  glass  jar  in  which  are  immersed 
pieces  of  zinc  and  copper ;  you  have  probably  noticed  that  the 
liquid  in  which  they  are  immersed  is  slightly  blue  in  color,  this 
being  caused  by  putting  in  some  crystals.  The  object  of  these 
crystals  is  to  form  sulphuric  acid  in  which  the  chemical  action 
between  the  copper  and  zinc  is  readily  started,  with  the  result 
that  an  electric  current  is  generated ;  the  further  result  is  that 
the  zinc  is  gradually  eaten  away  by  this  action,  and  after  a 


CARE  AND  MANAGEMENT  OF  BOILERS  IOQ 

certain  length  of  time  has  to  be  removed.  Now  if  these  two 
metals  had  been  placed  in  a  jar  containing  pure  water  there 
would  have  been  none  of  this  action  taking  place. 

"Here,  then,  is  the  secret  of  boiler  pitting  and  corrosion ;  the 
whole  boiler,  if  the  water  is  allowed  to  get  in  acid  condition, 
becomes  like  an  immense  battery,  or  rather  a  collection  of 
small  batteries,  as  this  action  will  take  place  between  different 
parts  of  the  steel  of  which  the  boiler  is  constructed  as  well  as 
between  a  brass  feed  pipe  and  the  boiler  shell,  only,  of  course, 
it  will  not  be  so  rapid.  Hence  it  is  that  for  years  past  baskets 
containing  zinc  have  been  suspended  in  different  parts  of  the 
boiler  immersed  in  the  water,  as  the  zinc  is  much  more  easily 
attacked  by  galvanic  action  than  are  the  steel  and  iron  of  the 
boilers.  The  zinc  is  therefore  eaten  away,  and  theoretically, 
at  least,  the  various  parts  of  the  boilers  are  spared.  Later 
investigations  on  the  subject  have  developed  the  fact  that  even 
the  use  of  zinc  is  not  the  best  step  to  be  taken,  as  that  is  simply 
remedying  the  effects  without  removing  the  cause.  In  other 
words,  it  is  similar  to  trying  to  cure  a  headache  for  a  drunken 
man  after  every  night's  jag  instead  of  making  him  stop  drink- 
ing the  booze  and  preventing  the  headaches." 

"I  can  understand  that  argument  all  right,  all  right,"  said 
O'Rourke,  who  had  been,  for  him,  paying  very  close  attention 
to  McAndrew's  remarks. 

"These  later  experiments  which  I  refer  to  have  been  di- 
rected towards  preventing  the  boiler  water  from  getting  into 
an  acid  condition,  and  thereby  stopping  galvanic  action  and 
rust.  It  is  a  well-known  law  of  chemistry  that  alkalis  will 
counteract  or  neutralize  acids.  Plain  soda  ash,  or  sal  soda,  as 
it  is  called  commercially,  is  one  of  the  best  and  cheapest  of 
the  alkalis  obtainable,  hence  that  is  the  material  best  used  for 
counteracting  acids  in  boiler  feed  water.  It  is  also  used  to 
"kill"  grease  and  oils  which  get  into  the  feed  water.  Soda 
and  zinc  have  for  many  years  been  relied  upon  to  correct  all 


17°  MC  ANDREW'S  FLOATING  SCHOOL 

of  the  evils  which  beset  marine  boilers,  and  yet  they  continue 
to  rust,  pit  and  eat  away. 

"By  a  long  and  continued  series  of  tests  recently  held,  some 
curious  facts  have  been  learned  regarding  the  use  of  soda  in 
feed  water.  One  is  that  a  small  amount  of  soda,  about  one- 
tenth  of  i  percent,  is  less  corrosive  than  neutral  water,  or 
water  that  is  neither  acid  nor  alkaline ;  another  is  that  water 
above  one-tenth  of  i  percent,  and  up  to  2.6  percent  alkaline, 
is  really  more  corrosive  in  its  effect  than  water  in  its  neutral 
state.  Finally,  these  experiments  demonstrated  that  water 
containing  3  percent  and  over  of  the  alkaline  solution  is  ab- 
solutely non-corrosive. 

"But  the  addition  of  such  much  ordinary  soda  to  a  boiler 
in  which  necessarily  there  are  some  oils  or  grease,  will  in- 
variably cause  violent  foaming,  or  priming,  as  it  is  sometimes 
called.  This  is  prevented  by  mixing  with  the  soda  certain 
proportions  of  glucose  and  a  substance  known  as  'cutch/ 
which  is  a  form  of  tannic  acid.  These  ingredients  tend  to  pre- 
vent foaming  and  the  formation  of  scale.  These  materials  are 
combined  in  standard  makes  of  boiler  compounds,  and  if  they 
are  properly  used  there  is  little  doubt  but  that  pitting  and 
rusting  will  cease  to  a  great  extent.  In  order  to  get  a  3  percent 
solution  of  the  boiler  water  it  is  necessary  to  add  about  $1A 
pounds  of  this  compound  for  each  ton  of  water  in  the  boiler. 

"Heretofore  the  care  of  boilers  has  been  very  much  on  the 
order  of  quackery  in  dosing  the  human  system  with  all  kinds 
of  patent  nostrums.  There  are  but  few  medicines  given  by 
doctors  which  really  accomplish  any  good,  and  they  have  been 
developed  by  experimenting.  Many  a  good  man  has  lost  his 
life  by  having  various  kinds  of  'dope'  tried  out  in  his  stomach, 
and  many  a  good  boiler  has  met  an  untimely  end  by  ignorant 
treatment.  Now  the  'boiler  doctors'  are  really  studying  the 
subject,  and  from  this  time  on  boilers  will  be  given  better 
treatment.  You  young  men  are  coming  into  the  business  at  a 


CARE  AND   MANAGEMENT  OF  BOILERS 


171 


time  when  the  new  methods  of  treating  boilers  are  being 
perfected,  and  I  predict  that  by  the  time  you  get  in  charge  of 
steam  machinery  you  will  know  much  better  how  to  take  care 
of  your  boilers  than  engineers  have  in  the  past. 

"No  matter  how  well  you  treat  the  boilers  while  running 
they  must,  at  certain  periods,  be  given  an  overhauling,  and  at 
such  times  the  greatest  care  and  attention  must  be  given  them. 

"The  fire  surfaces  must  be  thoroughly  cleaned  and  all  de- 
posits of  soot  brushed  off.  The  water  surfaces  must  be  given 
the  closest  attention,  and  particular  care  taken  to  clean  all 
dirt  and  scale  off  the  crown  sheets  or  tops  of  the  furnaces.  As 
you  all  know,  this  is  no  easy  job,  especially  with  Scotch 
boilers,  as  the  spaces  in  which  a  man  has  to  work  are  neces- 
sarily cramped,  the  air  he  breathes  is  vile,  and  there  is  every 
condition  which  would  make  him  shirk  the  work,  yet  if  the 
cleaning  and  scaling  are  not  done  properly  the  boiler  and  the 
coal  pile  will  suffer  alike. 

"To  give  you  an  idea  of  the  bad  effect  of  even  a  slight 
amount  of  scale  on  the  heating  surfaces  of  a  boiler,  you  will 
be  surprised,  I  know,  to  learn  that  a  hard  scale  only  one- 
twentieth  of  an  inch  thick  reduces  the  efficiency  of  a  boiler 
1 1. 1  percent.  That  is,  if  a  boiler  is  scaled  up  to  that  thickness 
on  its  heating  surfaces,  for  every  hundred  tons  of  coal  con- 
sumed there  will  be  an  absolute  loss  of  n.i  tons  in  the  steam- 
producing  effect." 

"That  would  very  nearly  pay  the  fireman's  wages,  wouldn't 
it?"  inquired  Nelson. 

"Yes,  and  more  than  pay  them,  so  you  can  see  the  neces- 
sity for  keeping  boilers  clean. 

"Soot  on  the  fire  surfaces  has  almost  as  bad  an  effect,  so 
you  can  understand  how  important  it  is  to  blow  the  tubes 
while  running." 

"The  company  ought  to  pay  us  extra  every  time  we  blow 
tubes,"  suggested  O'Rourke. 


172  MC  ANDREW  S  FLOATING  SCHOOL 

"That's  where  you  are  wrong,  as  usual,  O'Rourke.  Em- 
ployers in  these  days  pay  people  to  look  after  their  interests 
in  every  way,  and  because  a  man  is  a  .fireman  doesn't  mean  that 
he  is  for  the  sole  purpose  of  shoveling  coal  in  the  furnaces.  It 
is  the  fellow  who  thinks  what  he  can  do  to  save  his  employers 
money  by  keeping  the  particular  piece  of  machinery  which 
he  is  handling  up  to  the  highest  state  of  efficiency  who  gets 
promoted  and  carries  away  the  most  coin  on  pay  day. 

"When  cleaning  boilers  it  is  very  important  that  all  the 
valves  and  attachments  be  given  a  thorough  inspection  and  put 
in  first-class  condition.  All  screw  valve  stems  should  be  oiled 
with  cylinder  oil  and  graphite,  glands  repacked,  safety  valve 
lifting  gear  oiled  and  made  to  work  easily.  Small  pin-head 
leaks  should  be  touched  up  with  a  calking  tool  as  soon  as  they 
are  noticed.  A  leak  in  a  boiler  should  be  treated  in  accord- 
ance with  the  old  saying,  'A  stitch  in  time  saves  nine.' 

"Many  people  have  the  idea  that  a  fireman  to  be  successful 
need  only  be  sufficiently  strong  to  stand  the  heat  and  shovel 
coal  in  the  furnace  for  a  period  of  four  hours  at  a  time.  That 
is  a  great  mistake,  as  the  successful  operation  of  marine  ma- 
chinery depends  more  upon  skillful  firing  than  upon  any  other 
part  of  the  business.  No  man  can  be  a  successful  marine  engi- 
neer unless  he  knows  how  coal  can  be  burned  most  efficiently, 
and  sees  to  it  that  what  he  knows  in  that  line  is  put  into  force 
by  the  gang  in  the  fire-room.  The  average  fireman  if  left  alone 
to  follow  his  inclination  will  nearly  always  fill  up  his  furnaces 
to  the  top,  under  the  mistaken  idea  that  a  'crown-sheeter,'  as 
it  is  termed,  makes  the  most  steam.  The  average  fire-room 
watch  will,  if  'not  instructed  otherwise,  as  soon  as  they  come 
on  duty  clean  their  quota  of  fires,  usually  about  one  of  every 
three,  fill  up  the  furnaces,  then  sit  down  and  smoke  for  an 
hour  or  so.  The  boilers  will  also  smoke  under  such  treatment 
and  make  about  as  little  steam  as  possible. 


CARE  AND  MANAGEMENT  OF  BOILERS  173 

"In  order  to  get  the  best  results  the  following  rules  should 
be  stuck  to  closely : 

"Carry  the  fires  for  natural  draft  not  over  8  or  10  inches 
thick ;  if  forced  draft  is  used  they  should  be  about  a  foot  thick. 

"Put  on  only  two  or  three  shovelfulls  at  a  time  in  each 
furnace — throw  it  on  quickly  and  spread  it  evenly  over  the  fire. 

"Never  open  more  than  one  furnace  door  at  a  time,  and 
close  it  just  as  soon  as  possible. 

"Never  throw  in  any  lumps  larger  than  a  man's  fist;  have 
the  coal  passer  exercise  himself  by  using  a  coal  maul  on  larger 
lumps  before  putting  the  coal  in  the  furnace. 

"Only  use  a  slice  bar  to  remove  clinkers  or  ashes,  and  to 
keep  the  fires  bright  from  the  under  side. 

"Keep  the  ash  pans  clear  at  all  times. 

"Clean  only  one  fire  at  a  time,  and  so  regulate  the  periods 
between  cleanings  that  they  come  regularly,  if  the  coal  is  of 
uniform  quality;  otherwise  clean  them  whenever  they  get 
dirty. 

"If  the  draft  is  strong  and  the  coal  very  fine  and  dusty, 
sprinkle  a  little  water  on  the  coal. 

"Keep  the  fires  of  even  thickness  by  the  use  of  the  hoe  or 
rake ;  level  them  off  every  other  time  that  coal  is  thrown  into 
the  furnaces. 

"Have  each  watch  get  out  its  ashes  before  being  relieved, 
otherwise  there  will  be  a  scrap  with  the  next  watch. 

"In  general,  have  everything  done  in  the  fire-room  with 
some  snap." 

"In  other  words,"  butted  in  O'Rourke,  "put  some  ginger  into 
the  work." 

"Yes,  that's  it ;  let  the  'ginger-snap'  be  the  motto  of  the  fire- 
room." 

"It's  more  likely  to  be  the  hardtack,"  suggested  the  Hiber- 
nian. 


174  MC  ANDREW  S  FLOATING    SCHOOL 

"That's  true,  too,  unless  you  use  your  brains  as  well  as  your 
muscles." 

"Won't  you  tell  us  something  about  a  water-tender's  duties?" 
asked  Pierce,  who  was  feeling  the  responsibility  of  his  new 
job. 

"I  was  just  coming  to  that,"  replied  McAndrew.  "The  suc- 
cess of  the  fire-room  depends  largely  upon  the  water-tender ; 
the  engineer  of  the  watch  may  issue  all  the  instructions  about 
firing  that  he  wants  to,  but  he  can't  be  in  the  fireroom  all  the 
time  to  see  that  they  are  carried  out.  Hence  a  rattling  good 
water-tender  is  very  necessary.  Primarily  he  wants  to  be  a 
man  of  nerve,  quick  to  think  and  quick  to  act,  and  it's  not  a 
bad  asset  for  him  to  be  able  to  lick  any  fireman  or  coal-passer 
in  his  watch.  Not  that  he  should  resort  to  tactics  of  that 
kind — far  be  it  from  me  to  suggest  any  such  cruel  procedure — 
but  I  have  noticed  in  my  several  years  of  climbing  that  a 
water-tender  who  is  handy  with  his  fists  generally  keeps  the 
ginger  in  the  ginger-snap  with  his  men.  His  principal  job  is  to 
keep  his  mind  on  his  duties  during  every  minute  he  is  on 
watch,  and  to  keep  his  eye  on  the  gage-glasses  at  least  once 
every  minute. 

"He  must  also  see  that  the  furnaces  are  charged  regularly 
in  accordance  with  his  instructions ;  that  the  fire-room  is  kept 
clean;  that  the  coal  is  tallied;  that  the  ash  pans  are  hauled 
and  the  ashes  blown  out,  and,  in  general,  that  all  the  routine 
duties  of  the  fire-room  are  kept  up.  Ordinarily  he  should  see 
that  the  water  is  maintained  at  about  half  a  glass,  and  that  the 
feed  is  so  regulated  by  the  check  valves  that  it  remains  steady 
at  that  height  if  possible.  As  long  as  a  boiler  is  under  steam 
and  the  engines  running,  the  feed  should  never  be  entirely  cut 
off — no  boiler  has  ever  yet  been  blown  up  by  having  too 
much  water  in  it,  so  there  is  no  danger  to  the  boiler  even  if 
you  do  put  too  much  water  in  it — sometimes  there  is  danger 
to  the  engine  on  account  of  foaming,  caused  by  too  much 


CARE  AND  MANAGEMENT  OF   BOILERS  175. 

water.  In  general,  the  all-important  thing  to  guard  against  in 
tending  water  is  that  there  will  always  be  water  showing  in 
the  gage-glasses.  Low  water  is  the  cause  of  90  percent  of  all 
boiler  explosions,  and  in  nearly  every  case  it  is  a  direct  result 
of  carelessness. 

"In  case  the  water  does  get  out  of  sight,  as  it  will  do  at 
times  in  the  best  regulated  fire-rooms,  the  first  thing  not  to 
do  is  to  get  excited.  No  boiler  ever  has  blown  up  immediately 
after  the  water  has  dropped  out  of  sight.  Keep  cool  yourself 
and  try  to  cool  the  affected  boiler.  If  you  feel  positive  that 
the  water  level  is  only  a  little  below  the  bottom  of  the  glass, 
open  the  check  valve  wide  and  hold  your  breath.  You  may, 
during  your  first  experience,  think  that  it  is  taking  about  one 
month  and  ten  days  for  the  water  to  show  up,  but  in  reality  it 
is  usually  visible  in  four  or  five  minutes;  then  you  can  begin  to 
breathe  again.  If,  however,  the  water  is  out  of  sight,  and  you 
don't  feel  positive  of  the  last  time  you  saw  it,  close  the 
damper ;  put  up  the  ash-pit  doors ;  shut  off  the  main  and 
auxiliary  stop  valves  and  the  check  valve  and  throw  wet  ashes 
or  fresh  coal  over  the  fires  to  deaden  them.  Never  haul  the 
fires  out  until  they  have  been  deadened  or  extinguished  by 
water,  as  stirring  them  up  temporarily  causes  an  increased  heat, 
which  might  prove  disastrous. 

In  case  of  low  water,  the  first  thing,  of  course,  is  to  try  and 
remedy  it  by  cutting  out  the  boiler  affected,  as  above  de- 
scribed. But  the  water-tender  must  remember  that  the  other 
boilers  are  still  steaming,  and  he  must  not  neglect  to  see  that 
they  are  properly  looked  after,  notwithstanding  the  temporary 
excitement  on  account  of  the  crippled  boiler.  To  sum  it  all 
up,  a  good  water-tender  must  combine  attention  to  business, 
quickness  to  act,  and  imperturbability  of  the  highest  degree." 

This  last  qualification  simply  stunned  O'Rourke,  and  while 
he  was  trying  to  recover  from  the  shock  the  length  of  the 
word  had  given  him,  the  Chief  said :  "I  knew  that  would  hold 


176  MC  ANDREW'S  FLOATING  SCHOOL 

you,  O'Rourke;  but  don't  be  alarmed,  it  simply  means  the 
quality  of  not  getting  rattled ;  you  have  your  share  of  it. 

"When  the  ship  arrives  in  port  and  the  boilers  are  to  be 
out  of  use  for  several  days,  the  fires  should  not  be  hauled,  but 
simply  allowed  to  die  out  gradually,  so  that  there  will  be  no 
sudden  cooling  of  the  boiler  shell.  It  is  usually  advisable  to  give 
them  a  good  blowing  off  from  both  the  bottom  and  surface 
blows.  After  the  steam  is  gone  they  should  be  pumped  up  full 
with  fresh  water,  putting  on  a  small  pressure  of  5  or  10  pounds 
to  make  sure  that  they  are  filled  up.  They  should  never  be 
emptied  by  blowing  off,  as  that  causes  too  sudden  cooling.  If 
the  boiler  is  to  be  cleaned  the  fires  should  be  allowed  to  die 
out  and  the  water  pumped  out  after  the  steam  has  disappeared. 

"If  the  boiler  is  to  stand  full  of  water  for  any  length  of 
time,  the  water  should  be  made  alkaline,  so  as  to  prevent  cor- 
rosion as  far  as  possible. 

"If  the  ship  is  to  be  laid  up  great  care  should  be  paid  to 
putting  the  boilers  in  such  condition  that  they  will  not  de- 
teriorate. The  grate-bars  and  furnace  fittings,  ash  pans,  etc., 
should  be  taken  out  and  stacked  up  in  the  fire-room,  out  of 
the  way  but  in  a  convenient  position  to  be  replaced.  The  in- 
terior of  the  furnaces,  the  combustion  chambers  and  the  tubes 
should  be  thoroughly  brushed  and  cleaned  to  remove  all  soot 
and  ashes.  They  should  then  be  given  a  coating  of  black  oil 
all  over.  The  inside  or  water  surfaces  should  be  thoroughly 
cleaned  and  then  thoroughly  dried  out  by  starting  a  light  wood 
fire  in  the  furnaces  for  a  few  moments,  and  by  burning  pans 
of  charcoal  inside  the  boiler.  Some  people  prefer  to  fill  the 
boilers  up  solid  with  water  when  they  are  to  be  laid  up  for 
several  months,  but  I  prefer  to  have  them  laid  up  dry  as  I  have 
described.  All  the  valves  should  be  overhauled;  put  in  good 
condition,  and  the  valve  stems  coated  with  heavy  oil  or  grease. 
A  hood  should  be  placed  over  the  smokestack  in  order  to  keep 
the  rain  from  leaking  down  and  running  into  the  up-takes. 


CARE  AND   MANAGEMENT  OF  BOILERS  177 

"I  could  tell  you  lots  more  about  the  care  of  boilers,  as  you 
must  remember  that  it  is  almost  an  inexhaustible  subject. 
However,  I  have  touched  on  the  high  spots  of  care  and  man- 
agement, and  you  must  learn  much  more  by  reading  and  from 
experience,  the  greatest  teacher  of  all." 

"They  say  old  Experience  is  a  hard  teacher,"  suggested 
O'Rourke. 

"You  will  find  that  he  is  if  you  don't  follow  the  rules  of 
his  school." 

"What  are  they?" 

"His  schools  on  board  ship  require  diligence,  energy  and 
sobriety;  if  those  three  are  lived  up  to  you  will  find  the  old 
fellow  is  rather  an  easy  teacher." 


CHAPTER   XIX 

Care  and  Management  of   Engines  and 
Auxiliaries 

The  Tuscarora  arrived  in  New  York  and  was  loaded  for 
her  first  trip  South  after  the  extensive  repairs  she  had  under- 
gone. The  chief  had,  of  course,  been  so  busy  attending  to 
getting  the  vessel's  stores,  etc.,  ready  for  her  regular  trips 
fliat  he  had  paid  .no  attention  to  his  class  other  than  to 
caution  them  to  keep  on  with  their  studies  and  to  learn  as 
much  as  they  could  from  observation,  keeping  in  mind  what 
he  had  told  them  about  the  various  parts  of  the  machinery. 

There  was  a  new  second  assistant  by  the  name  of  Davis  on 
board,  and  he  had  been  placed  in  charge  of  the  boilers.  Coming 
into  the  fire-room  suddenly  one  day  he  found  O'Rourke  de- 
livering a  lecture  to  a  couple  of  coal  passers  on  how  steam 
was  generated.  "This  blatant  heat,"  he  was  saying,  "is  what 
makes  you  fellows  hustle  out  the  coal ;  it's  like  shoveling  snow 
in  the  East  River  to  make  the  tide  rise ;  you  don't  seem  to  get 
a  run  for  your  money  until  all  of  a  sudden — 'biffo,'  the  steam 
shows  on  the  gage !" 

Davis  could  stand  it  no  longer,  and  said,  "Cut  that  out, 
O'Rourke,  and  get  down  to  work — what  do  you  know  about 
steam,  anyhow?"  This  highly  incensed  the  shining  light  of 
the  Floating  School,  and  he  replied  rather  impudently  that  he 
"was  only  trying  to  give  these  ginks  a  little  scientfic  dope." 
Later  in  the  day  O'Rourke  complained  to  the  chief  that  the 
second  assistant  had  cut  short  his  efforts  at  enlightening  the 
coal  passers  on  matters  he  had  learned  at  the  school,  but  he 
was  told  to  pay  more  attention  to  his  work  and  not  to  bother 


CARE   AND    MANAGEMENT   OF    ENGINES  179 

with  imparting  his  knowledge  to  an  unappreciative  audience. 

The  ship  sailed  from  New  York  at  her  scheduled  time,  and 
was  soon  bucking  into  a  southeaster  as  she  headed  down  the 
coast.  It  cleared  off  the  next  day,  and  as  everything  was 
working  smoothly  the  chief  rounded  up  his  class  that  after- 
noon, all  of  them  being  off  watch,  and  proceeded  to  give  them 
some  further  instruction. 

He  began  his  remarks  by  saying  that  it  was  a  most  unusual 
thing  for  a  chief  engineer  of  a  vessel  to  take  time  while  his 
vessel  was  underway  to  be  holding  a  school  for  his  men,  but 
as  he  had  only  a  little  further  to  go  in  his  remarks  he  was 
determined  to  finish  the  job  up,  even  if  he  did  have  to  defy 
all  precedents. 

"Having  told  you  something  about  the  care  and  manage- 
ment of  boilers,  I  propose  this  afternoon  to  give  you  some 
hints  on  the  care  and  management  of  the  main  engine  and  the 
various  auxiliaries  in  the  engine  room. 

"An  engineer  standing  a  watch  at  sea  has  so  many  things  to 
attend  to  that  to  enumerate  them  all  would  fill  a  book  in  itself. 
Probably  no  other  business  requires  so  much  alertness  and 
quick  acting  and  thinking  as  a  marine  engineer  is  called  upon 
to  do  in  the  proper  performance  of  his  duties.  Every  faculty 
which  God  has  given  him  is  called  into  use.  Unlike  locomo- 
tive and  stationary  engineers,  he  must  never  allow  his  engines 
to  stop  for  days  and  days  at  a  stretch.  A  locomotive  will  be 
driven  for  five  or  six  hours  and  then  run  into  a  roundhouse 
for  a  rest;  a  stationary  engine  will  be  run  for  ten  or  twelve 
hours  and  then  stopped;  but  it  is  very  seldom  that  a  marine 
engine  is  ever  stopped  or  even  slowed  down  in  a  voyage  last- 
ing very  often  a  week,  or  even  two  weeks  at  a  time.  To  do 
this  successfully  requires  the  highest  degree  of  skill,  and  above 
all  things  the  closest  attention  to  even  the  most  minute  de- 
tails, as  the  derangement  of  even  a  very  small  part  of  an 
engine  often  results  in  a  serious  breakdown  at  a  critical 


i8o  MC  ANDREW'S  FLOATING  SCHOOL 

moment.  Remember,  young  men,  that  to  be  successful  in  your 
business  as  an  engineer  there  is  no  detail  about  the  entire 
mechanism  of  a  ship  that  is  too  trivial  to  demand  your 
closest  attention. 

"Preparations  for  getting  underway  for  a  long  trip  at  sea 
should  begin  early  in  the  morning  of  sailing  day.  If  repairs 
or  adjustments  have  been  made  during  the  stay  in  port,  the 
engineer  should  personally  see  that  every  set-screw  on  the 
moving  parts  is  set  up  tight;  that  all  the  bearings  have  been 
oiled  around  by  hand;  that  all  oil  cups  are  filled;  that  the 
sight-feeds  are  properly  adjusted  and  in  working  condition. 
To  make  sure  that  all  parts  of  the  main  engine  are  clear,  it 
is  well  to  turn  the  engine  at  least  once  clear  around,  either 
by  hand  or  with  the  jacking  engine.  After  this  is  done  he 
should  personally  see  that  the  worm  of  the  turning  gear  is 
thrown  out  of  gear;  failure  to  do  this  has  cost  many  a  man 
his  job. 

"The  first  thing  to  do  is  to  start  the  circulating  pump  slowly 
and  get  the  condenser  cooled  off  and  ready  for  the  exhaust 
steam.  An  hour  or  more  before  time  to  start,  depending  upon 
the  size  of  the  engine,  steam  should  be  admitted  slowly  to  the 
steam  jackets  around  the  cylinders,  if  there  are  any,  if  not 
steam  can  be  let  into  the  cylinders  direct  by  cracking  the 
throttle  slightly  and  opening  the  by-pass  valves.  All  drain 
valves  from  cylinders  and  valve  chests  must  be  kept  open  to 
the  condenser,  as  steam  striking  the  cold  cylinder  walls  is 
immediately  turned  into  water,  and  should  be  allowed  to  drain 
into  the  condenser. 

"The  warming  up  of  large  iron  castings  must  be  done  slowly 
and  thoroughly — never  make  haste  in  this  process  unless  in  a 
great  emergency.  After  the  cylinders  are  too  hot  to  bear  your 
hand  on  them,  and  having  ascertained  from  the  people  on 
deck  that  sufficient  mooring  lines  are  out,  steam  may  be  ad- 
mitted to  the  engine  very  slowly  at  first,  and  the  turns  gradu- 


CARE   AND    MANAGEMENT   OF    ENGINES  l8l 

ally  increased  to  not  more  than  half-speed.  The  reversing 
engine  should  be  tried  back  and  forth  a  number  of  times  to 
see  that  it  works  satisfactorily,  and  to  see  that  the  main 
engine  will  run  well  in  the  backing  gear.  The  water  service 
should  be  started.  The  drain  valves  should  be  kept  partly 
open  all  the  time  that  the  engine  is  being  warmed  up,  and,  in 
fact,  they  should  not  be  closed  altogether  until  the  vessel  is 
underway  from  the  dock  for  at  least  ten  or  fifteen  minutes. 

"Before  sailing  the  chief  engineer  has,  of  course,  satisfied 
himself  that  all  necessary  stores  are  on  board;  that  the  oil 
tanks  are  rilled  up,  and  that  all  wrenches  and  other  tools  for 
making  quick  repairs  or  adjustments  are  in  place  and  easy  of 
access. 

"Everything  now  being  ready,  and  the  captain  advised  of 
that  fact,  the  engineer  stands  by  the  throttle,  posts  a  man  at 
the  engine-room  telegraph,  which  has  been  previously  tried 
and  found  to  work  satisfactorily,  and  awaits  the  starting 
signal.  All  signals  from  deck  must  be  answered  promptly,  as 
in  working  away  from  the  dock  and  through  the  crowded 
harbor  any  delay  whatsoever  in  quickly  working  the  engine  as 
directed  would  be  dangerous.  Full  speed  is  seldom  ordered 
until  the  vessel  is  well  clear  of  the  harbor,  but  when  it  is 
rung  up  the  throttle  should  be  opened  only  to  such  an  extent 
that  the  engine  will  just  use  up  all  the  steam  that  the  boilers 
will  make,  and  will  maintain  a  uniform  number  of  revolutions. 
Fluctuations  of  the  steam  pressure  should  be  avoided  as  much 
as  possible,  and  so  far  as  he  is  able  the  engineer  on  duty 
should  strive  to  carry  uniform  boiler  pressure,  revolutions 
and  vacuum. 

"The  first  few  hours  of  a  run  the  man  on  watch  should  be 
unusually  alert  in  feeling  bearings,  especially  those  which  may 
have  been  recently  adjusted,  in  order  to  detect  the  first  sign 
of  unusual  heat.  When  a  bearing  starts  to  warm  up  it  gets 
'red  hot,'  as  the  saying  is,  in  very  short  order,  and  should  be 


182  MC  ANDREW'S  FLOATING  SCHOOL 

given  instant  attention.  The  causes  of  hot  bearings  are  in 
most  cases  due  to  being  set  up  too  tight  or  else  from  insuf- 
ficient oil  supply.  Occasionally  heating  is  due  to  the  presence 
of  grit,  but  that  can  only  result  from  rank  carelessness  in  not 
having  the  bearings  sufficiently  covered  up  or  otherwise  pro- 
tected when  the  engine  is  not  in  use." 

"How  do  you  cool  a  hot  journal  without  stopping  the 
engine?"  inquired  Nelson. 

"Put  cold  water  on  her,  of  course,  the  same  as  you  would 
cure  a  headache,"  volunteered  O'Rourke. 

"That's  the  very  last  thing  you  should  do,"  continued  the 
chief.  "The  first  thing  is  to  give  it  a  large  dose  of  oil,  and 
in  nine  cases  out  of  ten  you  will  find  that  it  will  gradually 
cool  off  from  that  treatment.  If  it  persists  in  heating  up  after 
yon  are  sure  that  it  is  getting  plenty  of  oil  get  out  the  proper 
wrenches  and  slack  off  the  nuts  a  trifle.  This  generally  ac- 
complishes the  object  sought,  but  if  even  that  method  fails 
then  resort  to  the  water  service,  as  sparingly  as  possible,  but 
just  enough  to  keep  down  the  heat.  If  the  ship  was  running 
in  fresh  water  the  effect  would  not  be  so  bad,  but  salt  water 
on  a  bright  journal  is  harmful." 

"I  get  you,  chief,"  broke  in  the  effervescing  O'Rourke. 
"Curing  a  hot  bearing  is  just  like  curing  a  man  of  a  stomach 
ache.  If  it  isn't  very  bad  give  him  a  dose  of  castor  oil;  if 
it  gets  worse  put  on  a  mustard  plaster ;  if  that  don't  work  give 
him  an  injection  of  fresh  water,  not  salt,  as  that  would  hurt 
him." 

"Your  powers  of  comparison  are  certainly  well  developed, 
O'Rourke,  but  I  fail  to  see  the  similarity  between  slackening 
up  a  bearing  and  putting  on  a  mustard  plaster." 

"Well,  if  that  mustard  plaster  attends  to  its  business  all 
right  the  man  will  want  to  slack  it  up,  you  can  bet." 

"Chief,  will  you  please  give  us  some  points  on  oiling,"  sug- 
gested Pierce,  who  was  feeling  the  responsibility  of  his  new 
job. 


CARE   AND    MANAGEMENT   OF    ENGINES  183 

"I  was  just  coming  to  that  important  subject,"  replied  the 
instructor.  "Oiling,  like  water  tending,  is  a  very  important 
job  on  board  ship.  Although  people  refer  in  a  slurring  man- 
ner to  the  'greasers'  there  are  few  jobs  anywhere  which  have 
the  importance  of  a  marine  oiler.  A  little  inattention  to  his 
duties  may  result  in  doing  great  damage  to  the  machinery, 
and  may  even  stop  or  cripple  the  ship.  An  oiler  in  his  rounds 
must  be  as  regular  as  clock  work,  and  constantly  on  the  alert 
with  his  senses  of  feeling,  hearing,  seeing  and  even  smelling. 
To  a  trained  oiler  all  these  senses  come  into  play.  By  feeling 
of  revolving  crankpins,  eccentric  straps,  main  journals,  etc., 
with  his  hands  he  can  tell  instantly  if  any  of  them  are  over- 
heated, or  even  if  they  show  a  tendency  to  heat  To  his  sensi- 
tive ear  the  first  discordant  noise,  even  the  slightest  squeak, 
will  indicate  that  some  bearing  or  journal  is  running  dry  and 
needs  immediate  attention.  His  eyes  must  be  sufficiently  keen 
of  vision  to  see  minute  and  almost  invisible  drops  of  oil  pass- 
ing down  the  tubes  of  automatic  oilers,  and  at  times  to  dis- 
cern even  the  slightest  sign  of  smoke,  which  would  indicate 
an  overheated  bearing.  His  sense  of  smell  is  called  into  play 
to  detect  the  first  indication  of  overheated  oil  or  grease." 

"What  about  his  sense  of  humor,"  inquired  Schmidt. 

"Every  oiler  must  have  that  sense  well  developed  also,  as 
his  main  object  is  to  prevent  any  squeaks  or  groans  from  the 
bearings  under  his  charge. 

"In  giving  advice  to  you  on  oiling  I  want  first  to  warn  you 
against  putting  too  much  dependence  on  automatic  oiling  gear 
of  any  kind.  Such  apparatus  is  all  right  when  it"  works  well, 
and  I  must  say  that  it  does  work  well  for  99  percent  of  the 
time ;  but  there  is  always  that  small  percentage  of  the  time 
when  it  does  not  work  well  that  you  must  guard  against.  A 
change  in  the  temperature  of  the  air  surrounding  a  needle 
valve  on  oil  reservoirs  will  often  change  the  adjustment  of 
the  drip,  so  that  the  bearing  to  which  it  directs  the  flow  of  oil 


184  MC  ANDREW'S  FLOATING  SCHOOL 

will  not  receive  a  sufficient  quantity  and  become  heated.  The 
same  trouble  might  be  started  by  a  small  speck  of  dirt  or  grit 
getting  under  the  valve.  Therefore  these  contrivances  must 
be  given  very  close  attention. 

"Many  engineers  prefer  the  old-fashioned  wick  feeds,  as 
they  are  much  more  positive  in  their  action,  although  not  quite 
so  easily  adjusted. 

"Most  oilers,  and  especially  beginners,  use  entirely  too 
much  oil,  both  from  oiling  by  hand  and  from  the  automatic 
feeds.  However,  this  tendency  is  quite  easily  regulated  by  the 
system  of  putting  every  man  on  an  allowance  for  his  watch. 
The  good  oiler  usually  finds  his  allowance  to  be  ample, 
•whereas  the  negligent  man  and  the  inexperienced  man  have  to 
hustle  to  keep  things  running  cool  on  the  amount  given  them. 

"A  routine  should  be  established,  the  time  between  oilings 
being  regulated  to  suit  the  speed  of  the  engine  and  the  neces- 
sity for  the  oil.  Usually  crankpins  and  eccentric  straps  should 
be  oiled  by  hand  once  each  twenty  minutes;  the  main  journals, 
link  gear,  etc.,  once  each  half  hour.  An.  inspection  of  the 
thrust  bearing,  spring  bearings  and. stern  tube  gland  once  each 
half  hour  is  usually  sufficient.  Piston  rods  and  valve  stems 
should  be  swabbed  every  half  hour,  but  as  little  oil  as  possible 
should  be  used  each  time,  as  it  is  by  this  means  that  oil  gets 
inside  the  cylinders,  is  carried  into  the  condenser  and  then 
pumped  into  the  boilers.  This  is  an  evil  that  must  be  guarded 
against  as  much  as  possible. 

"On  many  modern  ships  no  oil  whatever  is  used  to  lubricate 
the  main  engine  pistons  and  valves ;  if  any  lubricant  is  neces- 
sary many  engineers  use  graphite  mixed  with  water.  As  a 
matter  of  fact  in  engines  using  piston  valves,  internal  lubrica- 
tion is  not  absolutely  necessary.  The  cylinder  walls  are 
always  at  a  less  temperature  than  the  entering  steam;  conse- 
quently some  of  the  steam  is  condensed,  and  the  water  formed 
by  this  condensation  acts  as  a  lubricant. 


CARE   AND    MANAGEMENT   OF    ENGINES  185 

"On  the  smaller  engines,  used  as  auxiliaries,  such  as  pumps, 
blowers  and  dynamos,  internal  lubrication  seems  to  be  more 
of  a  necessity,  and  it  is  by  this  means  that  oil  gets  into  the 
feed  water  and  later  into  the  boilers.  The  introduction  of  the 
steam  turbine  for  driving  dynamos  and  pumps  does  away 
with  this  danger,  as,  of  course,  no  oil  is  necessary  for  the  in- 
terior of  turbines. 

"Many  engineers  prefer  to  use  grease,  or  compound,  as  it 
is  termed,  on  small  journals,  and  on  those  which  have  but 
little  friction.  Cups,  known  as  compression  cups,  are  screwed 
to  the  caps  of  such  journals,  and  the  oiler,  by  simply  giving  a 
small  twist  to  the  screw  top  on  the  cup,  forces  enough  grease 
on  the  journal  to  last  sometimes  for  several  hours.  Some 
engineers  use  grease  for  thrust  bearings  and  tunnel  bear- 
ings, but  it  is  more  economical  to  use  oil.  On  well-designed 
thrusts  the  collars  on  the  shafts  are  made  to  run  in  a  bath 
of  oil,  which  is  kept  cool  by  salt  water  circulated  through  coils 
in  the  bottom  of  the  bearing. 

"Oil  should  be  caught  in  the  drip-pans  and  passed  through 
oil  filters,  of  which  there  are  several  good  types  on  the 
market,  after  which  it  can  be  used  over  again. 

"It  takes  experience  to  make  a  good  oiler,  but,  of  course, 
you  cannot  get  the  experience  without  actually  doing  the 
oiling.  In  your  first  attempts  you  will  do  well  if  you  only 
take  the  bark  off  your  knuckles,  and  perhaps  lose  a  finger  nail, 
while  feeling  the  crankpins  and  eccentric  straps.  This  is  a 
very  important  part  of  his  duties  and  can  be  learned  only  t)y 
practice.  One  good  rule  to  remember  is  never  to  feel  a 
rapidly-revolving  piece  of  machinery  that  is  running  toward 
you ;  wait  until  it  starts  to  go  away  from  you  and  then  feel 
it  very*  quickly.  No  day-dreamer  can  be  successful,  as  feeling 
of  crankpins,  etc.,  requires  quick  action.  Wherever  it  is  prac- 
ticable on  fixed  bearings  use  the  backs  of  your  fingers  to  feel 
with,  as  they  are  more  sensitive  to  heat  than  the  hardened 
working  surfaces  of  a  man's  hand." 


i86  MC  ANDREW'S  FLOATING  SCHOOL 

"Schmidt  ought  to  use  that  nose  of  his,  as  they  say  he  is 
very  sensitive  about  the  length  of  it,"  suggested  O'Rourke, 
who,  for  him,  had  been  silent  for  a  long  time. 

Schmidt  retaliated  by  saying  that  it  would  never  do  for 
O'Rourke  to  use  his  cheek  for  feeling  journals,  as  the  metal 
would  have  to  be  red  hot  for  him  to  even  notice  it  by  that 
method. 

McAndrew  called  them  both  down  hard  for  making  such 
personal  references,  and  said  that  oilers  were  supposed  to  be 
courteous  to  one  another.  If  they  are  not  there  might  be  all 
kinds  of  trouble  when  relieving  one  another  as  the  watches 
changed.  "The  man  about  to  be  relieved,"  said  he,  "must 
have  all  his  oil  reservoirs  filled  up  and  all  the  bearings  and 
journals  under  his  care  running  cool,  or  otherwise  the  oiler 
coming  on  watch  could  refuse  to  relieve  him. 

"I  hope,"  he  continued,  "that  O'Rourke  and  Schmidt  never 
have  to  relieve  one  another  from  oilers'  watches,  as  I  am 
afraid  they  would  both  be  standing  double  watches  the 
greater  part  of  the  time." 

"Chief,  won't  you  put  us  onto  some  of  the  duties  an  engi- 
neer has  to  do  in  port?"  suggested  Schmidt,  who  was  prob- 
ably the  most  eager  for  knowledge  of  any  in  the  class. 

"Certainly,"  replied  the  general  instructor.  "The  first  thing 
most  of  them  do  is  to  beat  it  for  their  own  homes,  or  some- 
one else's  home,  according  to  circumstances.  Of  course,  that 
is  natural,  as  a  man  who  stands  engine-room  watches  for  a 
week  or  more  at  a  stretch,  is  mighty  glad  to  hit  the  beach 
and  stretch  himself  out  in  a  four-poster  at  least  one  night 
in  ten;  but,  seriously  speaking,  there  are  many  important 
things  which  the  engineer's  gang  must  do  before  sailing  day 
arrives  again.  Nowadays  any  repairs  involving  machine  work 
of  any  description  is  put  into  the  shops,  as  the  engineer's 
force  usually  has  neither  time  nor  the  necessary  tools  for 
making  any  very  extensive  repairs.  The  work  most  usually 


CARE    AND    MANAGEMENT   OF    ENGINES  187 

performed  in  port  might  be  divided  up  under  four  headings. 
Cleaning  is  one  of  the  first  things  to  perform;  adjustment  of 
bearings  must  be  attended  to;  making  new  joints  and  pack- 
ing of  stuffing-boxes  must  be  performed,  and  examinations  of 
the  interiors  of  cylinders  and  the  auxiliaries  must  be  made 
periodically.  These  four  divisions  of  work  probably  constitute 
nine-tenths  of  the  duties  performed  in  port. 

"As  soon  as  the  jingle-bell  is  rung,  signifying  'through  with 
the  engine/  the  boys  should  be  set  to  wiping  the  engine  down 
and  cleaning  up  the  floor  plates.  Some  engineers  like  to  have 
a  small  injector  so  fitted  and  connected  up  that  it  can  be  used 
to  wash  down  the  bed-plates  and  bilges  with  hot  water;  but 
I  don't  believe  in  squirting  salt  water  indiscriminately  about 
an  engine  room,  as  it  is  bad  for  the  bearings  and  bright  work. 
Gaskets,  made  of  hemp,  loosely  laid  up,  should  be  laid  across 
both  ends  of  all  the  principal  journals  to  keep  out  any  dirt 
or  grit  which  might  be  around  while  the  engine  is  not  in  use. 
During  the  stay  in  port,  bulkheads  should  be  scrubbed  if  they 
have  become  dirty,  storerooms  cleaned  out  and  put  in  good 
order,  bilge  strainers  cleaned  thoroughly,  the  bilges  themselves 
cleaned  and  kept  well  painted,  the  filtering  material  renewed 
in  the  feed  tank,  and  in  a  general  way  the  whole  department 
given  such  cleaning,  painting  and  renovating  as  cannot  well 
be  done  while  the  machinery  is  running. 

'The  adjustment  of  bearings  is  probably  one  of  the  most 
important  duties  for  the  engineer  and  his  assistant.  If  a 
bearing  runs  a  little  slack  and  develops  a  slight  pound  it 
should  be  carefully  readjusted,  or  if  there  has  been  a  tendency 
for  any  particular  bearing  to  heat  up  during  the  trip  it  should 
be  examined,  and  if  necessary  overhauled  and  readjusted 
while  the  ship  is  at  the  dock." 

"Why  are  they  always  monkeying  with  the  crankpins  on  this 
ship?"  asked  O'Rourke.  "It  seems  to  me,"  he  continued, 
"that  that  is  all  one  of  the  assistants  does  while  this  ship  is 


I??-  MC  ANDREW'S  FLOATING  SCHOOL 

at  the  dock.  I  see  him  running  around  with  something  that 
looks  like  a  handful  of  spaghetti,  and  he  is  always  saying 
that  he  has  got  her  down  to  29,  or  some  number  like  that. 
You'd  think  he  was  running  a  keno  game.  Ke  ought  to " 

"Well,  O'Rourke,"  interrupted  the  chief,  "if  you're  running 
this  talkfest  I'll  quit  and  let  you  take  the  chair." 

"I'm  through,"  meekly  replied  the  Hibernian,  realizing,  for 
once  at  least,  that  he  was  sat  upon. 

''Bearings  lined  with  white  metal  are  now  almost  uni- 
versally used,"  said  McAndrew,  after  re-establishing  himself 
as  boss  of  the  school  room.  "These  wear  down  considerably 
during  long-continued  runs,  and  consequently  must  be  ad- 
justed more  often  than  the  old-fashioned  bearings  of  solid 
brass.  In  the  early  days  it  was  the  test  of  a  good  engineer 
to  make  adjustments  by  chipping  and  filing  down  the  edges  of 
the  brasses  uniformly,  as  that  was  the  method  then  in  vogue. 
All  bearings  in  these  times  have  pieces  of  brass,  known  as 
distance  pieces,  between  the  upper  and  lower  brasses;  when 
the  wear  has  been  excessive  these  distance  pieces  can  be 
planed  down  in  a  shaper  very  quickly.  However,  that  is  sel- 
dom necessary,  as  liners,  or  shims,  consisting  of  varying 
thicknesses  of  sheet  brass,  are  also  fitted  between  the  distance 
pieces  and  the  brasses.  By  removing  one  of  the  thinnest 
liners  a  very  small  lost  motion  can  be-  taken  up  and  the 
tendency  of  the  bearing  to  pound  prevented.  Of  course,  it  is 
necessary  to  have  some  slight  clearance  to  all  bearings,  else 
it  would  be  difficult  to  distribute  the  oil  over  the  rubbing  sur- 
faces. A  good  rule  to  remember  for  the  amount  of  the  clear- 
ance is  that  for  every  inch  of  diameter  of  a  bearing  there 
should  be  two  one-thousandths  of  an  inch  of  space.  Thus  for 
a  12-inch  crankpin  the  clearance  should  be  12  X  .002  —  .024 
inch.  This  corresponds  practically  to  No.  24  B.  W.  G.,  which 
is  a  safe  clearance  space.  Some  engineers  would  set  them 
up  tighter  than  that,  but  when  they  do  there  is  always  a  good 


CARE   AND    MANAGEMENT  OF   ENGINES  189 

chance  for  them  to  heat.  By  the  same  rule  a  6-inch  diameter 
crosshead  pin  should  have  .013  inch  clearance,  which  cor- 
responds to  No.  30  B.  W.  G." 

"What's  that  mean,  chief?"  asked  Pierce. 
"B.  W.  G.  means  'Birmingham  Wire  Gage.'  Wire,  you 
know,  is  made  of  a  great  many  different  diameters,  and  in- 
stead of  expressing  them  as  so  many  thousandths  of  an  inch, 
it  is  much  simpler  to  say  No.  i,  7  or  27,  or  whatever  it  hap- 
pens to  be.  Birmingham  in  England  is  one  of  the  leading 
wire  manufacturing  communities,  so  the  gage  most  generally 
used  is  the  one  which  was  adopted  at  that  place  many  years 
ago. 

"In  adjusting  a  bearing,  as,  for  example,  the  main  bearings 
of  the  engine,  the  cap  or  top  part  should  be  removed  by  means 
of  a  chain  hoist,  and  the  white  metal  and  oil  grooves  ex- 
amined. If  it  is  found  that  the  brass  does  not  bear  well  on  the 
shaft  journal  it  must  be  scraped  down  to  a  good  fit.  To  do 
this  properly  the  journal  should  be  smeared  over  with  a  thin 
coating  of  red  lead  and  oil  and  the  cap  put  back  in  place. 
Where  the  white  metal  of  the  brass  touches  the  shaft  there 
will  be  red  spots.  These  spots  should  all  be  carefully  scraped 
down  and  the  cap  again  tried  as  before.  A^ter  this  is  repeated 
several  times,  the  brass  should  be  found  to  bear  on  the 
journal  quite  uniformly.  Always  remember  that  the  principal 
bearing  should  be  in  the  center  of  the  brass.  The  outside 
edges  should  not  touch  at  all,  for  if  they  bear  on  the  journal 
when  it  is  cold  it  will  be  found  when  the  temperature  of  the 
bearing  rises  to  a  working  heat  there  will  be  a  tendency  for 
the  edges  to  squeeze  in  on  the  shaft;  or  nip,  as  it  is  termed, 
which  will  cause  the  bearing  to  become  overheated.  It  is  also 
necessary  to  fit  them  in  this  way  to  provide  for  wear,  the 
heaviest  of  which  is  naturally  in  the  center  of  the  brass.  After 
the  bearing  is  found  to  be  satisfactory,  so  far  as  its  surface  is 
concerned,  the  oil  grooves  should  be  carefully  cleaned  out,  and 


190  MC  ANDREW'S  FLOATING  SCHOOL 

enlarged  where  necessary,  as  it  is  of  vital  importance  to  have 
the  grooves  amply  large  and  so  placed  that  a  uniform  dis- 
tribution of  the  oil  will  take  place. 

"For  final  adjustments  three  strips  of  lead  wire  about  1/16 
inch  in  diameter  should  be  laid  across  each  journal,  one  at 
each  end  and  one  in  the  middle.  The  cap  should  then  be 
replaced,  and  the  main  bearing  nuts  set  down  as  tightly  as 
possible  by  means  of  a  box-wrench  and  a  sledge.  The  posi- 
tion of  the  nut  in  reference  to  the  end  of  the  bolt  should  be 
marked  with  a  scriber,  so  that  you  will  know  how  tight  to 
set  up  on  the  nuts  after  the  cap  has  again  been  taken  off  and 
the  three  pieces  of  lead  wire  removed.  The  leads,  as  they  are 
called,  should  be  measured  by  means  of  the  wire  gage,  to  see 
that  they  are  of  about  the  thickness  necessary  for  the  desired 
amount  of  clearance.  A  more  accurate  method  for  determin- 
ing the  amount  of  clearance  from  the  leads  is  by  means  of 
the  micrometer." 

"Mike  who?"  interrupted  O'Rourke. 

"Don't  let  that  word  bother  you,  as  the  instrument  is  not  an 
Irish  invention,  even  if  its.  first  name  is  Mike,"  rejoined 
McAndrew.  "It  is  more  than  likely  it  was  invented  by  a 
German;  but  at  any  rate  it  is  a  very  useful  measuring  ma- 
chine, by  means  of  which,  through  the  medium  of  an  ac- 
curately cut  screw  head  and 'a  graduated  sleeve,  thicknesses 
of  one-thousandth  of  an  inch,  and  even  of  one  ten-thousandth 
inch  can  be  readily  measured.  When  you  get  to  be  engineers 
you  will  find  it  very  useful  to  save  these  leads,  or  spaghetti, 
as  O'Rourke  calls  them,  for  future  reference.  A  convenient 
way  to  do  it  is  to  get  a  large  brown-paper  book,  a  scrap- 
book  will  do,  and  cut  slits  in  the  pages  through  which  the 
leads  can  be  held  in  place.  Mark  under  each  set  of  three  leads 
the  name  of  the  bearing  from  which  they  were  taken,  the  date, 
and  opposite  several  points  in  their  length  jot  down  the  thick- 
nesses in  thousandths  of  an  inch. 


CARE    AND    MANAGEMENT   OF   ENGINES 


IQI 


"Even  if  a  crankpin  has  been  adjusted  to  your  satisfaction 
by  means  of  leads,  it  is  always  a  wise  precaution  to  put  the 
end  of  a  pinch  bar  in  between  the  end  of  the  brass  and  the 
crank-web,  and  if  it  does  not  move  with  a  'chug'  after  a  quick 
yank  on  the  other  end  of  the  bar,  the  brasses  are  probably  too 
tight,  and  should  be  slacked  up  slightly  until  they  can  be 
moved  in  that  manner. 

"When  eccentric  straps  become  noisy,  they  should  be  taken 
apart  and  a  small  shim  removed ;  but  they  should  never  be 
set  up  so  tight  that  they  cannot  be  moved  all  around  by  hand 
after  the  bearing  surfaces  have  been  oiled. 

"Journals  connected  with  the  valve  gear  do  not  need  adjust- 
ing very  often,  but  when  they  do  it  is  a  comparatively  simple 
matter,  especially  if  they  are  fitted  with  strap,  gib  and  key 
connections,  as  many  of  them  are.  When  first  constructed  it 
is  usual  to  leave  from  1/16  inch  to  H  incn  clearance  between 
the  two  brasses,  so  to  adjust  them  afterwards  it  is  only  neces- 
sary to  drive  the  taper  key  in  a  little  further,  always  beingi 
sure  to  set  up  tightly  on  the  set  screw. 

"Many  small  pin  bearings  where  the  wear  is  trifling  are 
fitted  with  solid  bushings  of  brass.  When  they  become  badly 
worn  the  bushings  should  be  renewed. 

"The  making  of  new  joints  and  packing  small  stuffing- 
boxes  should  be  attended  to  while  the  vessel  is  in  port,  as  there 
is  nothing  that  annoys  an  engineer  more  while  the  vessel  is 
underway  than  to  have  one  of  these  blow  out.  It  is  a  strange 
fatality,  if  I  might  call  it  that,  that  joints  and  stuffing-boxes 
always  give  way  at  the  most  inopportune  times.  A  joint  will 
run  along  perfectly  tight  while  the  ship  is  in  a  cold  climate, 
but  just  as  soon  as  she  gets  down  South,  and  on  some  par- 
ticularly hot  day,  'bang!'  out  blows  the  gasket,  and  fills  an 
already  hot  engine  room  full  of  steam  and  vapor. 

"Then,  too,  it  is  generally  the  joint  which  is  hardest,  to  get 
at  which  lets  go,  while  some  joint  that  is  easily  remade  will 


192  MC  ANDREW'S  FLOATING  SCHOOL 

run  along  as  tight  as  a  bottle  for  months  at*  a  time.  The 
engineer  who  is  onto  his  job  will  have  all  suspicions  joints 
remade  while  the  vessel  is  tied  up  to  the  wharf  and  there  is 
time  to  do  the  job  properly. 

"The  making  of  joints  and  packing  of  stuffing-boxes  is 
something  you  will  have  to  learn  from  actual  experience. 
The  various  materials  from  which  gaskets  are  made  are  as 
numerous  as  the  first  man  up  San  Juan  Hill,  and  some  of 
them  just  about  as  reliable.  As  a  rule,  you  should  use  only 
rubber  gaskets  for  joints  in  water  pipes.  For  steam  joints 
various  fibrous  materials,  asbestos  woven  with  wire  and 
usudurian  are  the  best  and  last  longest.  In  making  steam 
joints  you  must  be  exceedingly  careful  to  see  that  all  the  old 
material  is  scraped  from  both  flanges,  and  that  the  flanges 
themselves  are  parallel.  The  holes  in  the  gasket  should  be 
cleanly  cut,  and  before  it  is  slipped  in  place  the  packing 
should  be  smeared  over  on  both  sides  with  black  lead  and 
tallow  or  cylinder  oil.  Set  up  on  the  bolts  just  as  tightly  as 
possible,  but  not  so  hard  as  to  twist  some  of  them  off,  as  is 
done  occasionally  by  muscular  young  men  like  O'Rourke." 

"Honest  Injun,  chief,  that  wasn't  me  that  twisted  that  stud 
off  the  feed  pump  this  morning.  I  won't  say  just  who  it  was, 
but  I  think  he  can  speak  German,"  protested  O'Rourke. 

"Oho !  so  one  of  you  is  guilty  of  that  very  same  thing  only 
this  morning,  eh?  Well,  whichever  one  of  you  highbrows  it 
was  will  have  the  pleasure  of  putting  in  a  new  stud  while  you 
are  resting  yourselves  off  watch  to-morrow. 

"As  I  was  saying,"  resumed  McAndrew,  "the  bolts  on  a 
new  joint  should  be  set  up  as  tightly  as  possible,  and  then 
after  steam  has  been  on  the  pipe  for  an  hour  or  so,  they 
should  be  followed  up,  as  the  saying  is,  as  the  heating  of 
the  gasket  usually  allows  a  little  more  tightening. 

"In  packing  stuffing-boxes,  the  turns  of  packing  should  be 
put  in  so  that  the  joints  do  not  come  opposite  one  another, 


CARE    AND    MANAGEMENT   OF    ENGINES  IQ3 

and  this  packing  should  also  be  rubbed  down  with  black  lead 
and  tallow." 

"Why  do  you  do  that,  chief?"  asked  Nelson. 

"It  isn't  that  it  does  any  particular  good  in  keeping  the 
stuffing-box  tight,  but  it  makes  it  much  easier  to  remove  the 
packing  when  it  is  worn  out  and  again  has  to  be  repacked. 
In  marine  engineering,  no  matter  what  you  do  in  the  way  of 
construction  or  repairs,  you  must  provide  for  all  manner  of 
things  which  may  happen  in  the  future.  You  don't  want  to  be 
caught  like  the  man  who  built  a  boat  having  a  6-foot  beam  in 
a  cellar  with  only  a  3-foot  door  to  get  it  out  of  and  didn't 
notice  the  difference  until  the  boat  was  finished. 

"Certain  parts  of  marine  machinery  need  to  be  inspected  to 
see  that  everything  is  in  good  condition.  I  don't  believe,  as 
some  engineers  apparently  do,  in  taking  an  engine  or  an 
auxiliary  apart  to  see  what  makes  it  work  so  well,  but  at  regu- 
lar periods,  say  every  three  or  four  months,  the  cylinder 
heads  should  be  lifted  to  see  that  none  of  the  follower  bolts 
is  cracked  or  has  become  loose.  Water  ends  of  air  pumps, 
feed  pumps  and  bilge  pumps  should  be  examined  quite  fre- 
quently to  see  that  the  valves  have  not  become  too  much  worn 
and  the  springs  are  not  broken  and  are  in  their  proper  places. 
This  is  particularly  necessary  if  rubber  valves  are  used.  The 
main  condenser  should  be  watched  closely  to  see  that  no  leaks 
have  developed  in  the  tubes.  This  is  generally  indicated  by 
the  water  getting  too  high  in  the  gage  glasses  on  the  boilers, 
as  salt  water  will  leak  through  the  tubes  to  the  fresh  water 
side  of  the  condenser  and  mix  in  with  the  feed  water,  causing 
a  surplus.  If  you  have  reason  to  suspect  that  any  of  the 
tubes  are  leaking  the  condenser  should  be  filled  with  water, 
the  water  chest  at  each  end  removed,  and  the  ends  of  all  the 
tubes  examined  carefully  to  see  if  any  water  is  running  out. 
If  it  does,  that  indicates  that  the  tube  is  leaking  and  it  should 
be  removed  at  once.  If  there  are  spare  tubes  on  hand  fit  one 


IQ4  MC   ANDREW  S    FLOATING    SCHOOL 

of  them  in  its  place  or  else  plug  up  the  holes  in  the  tube 
sheets. 

"After  several  months  of  use,  condenser  tubes  become 
covered  with  grease  from  the  exhaust  steam  and  fall  off  in 
their  efficiency  of  transmitting  the  heat  from  the  exhaust 
steam  to  the  circulating  water.  This  is  generally  indicated 
by  the  vacuum  falling  below  its  usual  height,  and  the  con- 
denser should  be  boiled  out  with  a  strong  solution  of  soda  and 
water  heated  by  means  of  a  jet  of  steam. 

"There  are,  of  course,  many  other  jobs  to  be  attended  to 
while  a  vessel  is  in  port;  in  fact,  the  duties  of  an  engineer 
while  the  vessel  is  tied  up  remind  me  of  the  tribulations  of  a 
12-year-old  playmate  of  mine  when  I  was  a  youngster.  He 
would  get  home  from  school  about  4  o'clock  in  the  afternoon, 
and  upon  reporting  to  his  fond  stepmother  would  every  day 
be  saluted  about  as  follows :  'Now,  Lewis,  you  hurry  up  and 
get  ten  or  twelve  baskets  of  chips  from  the  shipyard ;  run  up 
to  the  grocery  store  for  me;  hoe  five  rows  of  potatoes;  chop 
the  kindling  for  the  morning;  get  six  pails  of  water  and  then 
you  can  play  the  rest  of  the  time  before  supper.' 

"After  performing  all  the  numerous  chores  I  have  told  you 
about  which  have  to  be  done  in  port  the  average  engineer  who 
follows  the  sea  can  play  the  rest  of  the  time;  but  I  am  afraid 
that  it  is  mostly  after  supper  that  he  finds  the  opportunity." 


CHAPTER  XX 

Examination  Questions  and  Answers 

Since  the  last  lecture  to  his  class  McAndrew  had  been  so 
busy  with  his  regular  duties  that  nearly  a  month  had  elapsed 
before  another  opportunity  offered  to  give  the  boys  in  the 
Floating  School  further  instruction.  In  the  meantime  the 
four  young  men  had  continued  their  studies,  using  such  text- 
books as  they  had  on  hand  for  the  purpose.  It  seems  that 
Pierce,  who  was  somewhat  more  ambitious  than  his  ship- 
mates, had,  at  about  the  time  that  the  Chief  commenced  their 
instruction,  enlisted  as  a  student  in  one  of  the  large  cor- 
respondence schools  and  taken  up  its  course  in  marine  engi- 
neering. The  text-books  furnished  with  the  course  were  very 
comprehensive,  and  Pierce  had  kindly  loaned  them  to  his 
fellow  students,  so  that  all  had  profited  by  studying  them. 

McAndrew  commenced  his  remarks  by  saying,  "We  have 
now  covered,  in  a  somewhat  brief  manner,  to  be  sure,  nearly 
all  the  principal  subjects  necessary  for  an  elementary  under- 
standing of  marine  engineering.  It  is  now  up  to  you  to  put 
in  practice  some  of  the  things  I  have  told  you.  To  get  your 
'tickets'  as  assistant  engineers  is,  of  course,  your  ambition. 
The  best  way  to  prepare  for  your  examination  for  a  license 
is  to  work  out  some  of  the  questions  which  have  been  asked 
by  the  steamboat  inspectors.  The  existing  laws  in  the  United 
States  concerning  licenses  are  somewhat  vague  in  regard  to 
examinations,  and  I  will  quote  you  the  following  extracts 
from  the  statutes,  which  will  be  of  interest  to  you : 


196  MC  ANDREW'S  FLOATING  SCHOOL 

"  'No  person  shall  receive  an  original  license  as  engineer  or 
assistant  engineer  who  has  not  served  at  least  three  years  in 
the  engineer's  department  of  a  steam  vessel.  *  *  * 

"  'Any  person  who  has  served  three  years  as  apprentice  to 
the  machinist  trade  in  a  marine,  stationary  or  locomotive 
engine  works,  and  any  person  who  has  served  for  a  period  of 
not  less  than  three  years  as  a  locomotive  or  stationary  engi- 
neer, or  any  person  graduated  as  a  mechanical  engineer  from 
a  duly  recognized  school  of  technology,  may  be  licensed  to 
serve  as  an  engineer  of  steam  vessels  after  having  had  not 
less  than  one  year's  experience  in  the  engine  department  of 
steam  vessels,  a  portion  of  which  experience  must  have  been 
obtained  within  the  three  years  preceding  his  application, 
which  fact  must  be  verified  by  the  certificate  in  writing  of  the 
licensed  engineer  or  master  under  whom  the  applicant  has 
served,  said  certificate  to  be  filed  with  the  application  of  the 
candidate;  and  no  person  shall  receive  license  as  above,  ex- 
cept for  special  license,  who  is  not  able  to  determine  the 
weight  necessary  to  be  placed  on  the  lever  of  a  safety  valve 
(the  diameter  of  valve,  length  of  lever,  distance  from  center 
of  valve  to  fulcrum,  weight  of  lever,  and  weight  of  valve  and 
stem  being  known)  to  withstand  any  given  pressure  of  steam 
in  a  boiler,  or  who  is  not  able  to  figure  and  determine  the 
strain  brought  on  the  braces  of  a  boiler  with  a  given  pressure 
of  steam,  the  position  and  distance  apart  of  braces  being 
known,  such  knowledge  to  be  determined  by  an  examination 
in  writing,  and  the  report  of  examination  filed  with  the  ap- 
plication in  the  office  of  the  local  inspectors,  and  no  engineer 
or  assistant  engineer  now  holding  a  license  shall  have  the 
grade  of  the  same  raised  without  possessing  the  above  quali- 
fications. No  original  license  shall  be  granted  any  engineer 
or  assistant  engineer  who  cannot  read  and  write  and  does  not 
understand  the  plain  rules  of  arithmetic/ 

"So  far  as  the  letter  of  the  law  is  concerned  it  would  seem 


EXAMINATION    QUESTIONS    AND   ANSWERS  197 

to  be  very  easy  for  you  to  get  a  license,  providing  you  can 
solve  the  two  problems  called  for  in  the  above  qualification. 
But  do  not  fool  yourselves  by  thinking  that  you  can  get  away 
with  a  ticket  so  easily;  while  the  law  on  the  subject  is  very 
old  and  not  brought  up  to  date,  you  will  find  that  the  ex- 
aminers are  very  much  alive  to  present  conditions.  While  the 
law  requires  satisfactory  answers  to  only  those  two  ques- 
tions, it  does  not  prohibit  further  questioning  by  the  inspec- 
tors, and  if  you  ever  pass  your  examinations  you  will  find 
that  you  must  be  pretty  well  posted  in  about  every  subject 
connected  with  the  business." 

"Chief,"  inquired  O'Rourke,  "I  see  that  you  can  get  a 
ticket  inside  of  a  year  if  you  are  a  graduate — how  about 
graduates  from  our  school?" 

"I  am  afraid,"  replied  McAndrew,  "that  our  .little  school 
here  would  not  score  very  heavily  as  a  'fecognized  school  of 
technology' ;  but  do  not  be  alarmed  about  that.  Where  there 
is  one  licensed  marine  engineer  who  is  graduated  from  a 
'recognized  school  of  technology'  there  are  at  least  forty-nine 
who  have  graduated  from  the  College  of  Practical  Experience 
and  Self-Help.  This  little  Floating  School  of  ours  is  simply 
a  branch  of  that  college. 

"You  will  notice  that  the  law  requires  that  every  candidate 
must  understand  the  plain  rules  of  arithmetic.  I  know  that 
you  all  understand  these  rules,  but  I  am  not  so  sure  that  you 
all  understand  the  plain  rules  of  mensuration,  or  the  measure- 
ments of  area  and  volume.  No  one  can  pass  the  examination 
who  does  not  understand  these  rules,  so  I  will  devote  a  few 
moments  to  explaining  them  to  you. 

MEASUREMENT  OF  AREAS  AND  VOLUMES 

"To  find  the  area  of  any  plain  rectangular  figure,  that  is, 
one  having  four  square  corners,  you  multiply  the  length  by 


IQo  MC  ANDREW  S    FLOATING    SCHOOL 

the  breadth.  Thus  the  side  of  a  rectangular  tank  8  feet  long 
and  4  feet  wide  will  contain  8  X  4  =  32  square  feet. 

"To  find  the  volume  of  a  rectangular  tank  we  must  multiply 
the  length,  breadth  and  depth  together.  Thus  if  the  above 
tank  is  4  feet  in  depth  it  will  contain  8  X  4  X  4  —  128  cubic 
feet. 

"A  circle  is  defined  as  a  figure  every  point  of  whose  cir- 
cumference or  boundary  is  equally  distant  from  a  point  within 
called  the  center.  You  are  familiar  with  how  it  is  drawn  with 
a  pair  of  compasses.  The  diameter  of  a  circle  is  the  length  of 
a  line  drawn  across  it  and  through  its  center.  To  find  the 
length  of  the  circumference,  or  distance  around  the  circle,  we 
multiply  the  diameter  by  the  figures  3.1416.  Thus  if  the 
diameter  of  a  barrel  is  2  feet,  the  circumference  will  be  2  X 
3.1416,  or  6.2832  feet. 

"You  will  very  often  be  required  to  find  the  area  of  a 
circle ;  the  way  to  do  it  is  to  square  the  diameter ;  that  is, 
multiply  it  by  itself,  and  then  multiply  the  quotient  by  the 
figures  .7854.  If  you  are  told  that  a  high-pressure  cylinder  is 
30  inches  in  diameter,  to  find  its  area  you  first  multiply  30  X 
30,  and  get  900.  Then  900  X  -7854  =  706.86  square  inches, 
the  area. 

"You  must  always  remember  those  two  'constants/  as  they 
are  termed,  3.1416  for  the  circumference  and  .7854  for  the 
area  of  a  circle,  as  you  will  often  have  use  for  them  when 
you  do  not  have  time  to  hunt  them  up  in  the  text-books." 

"I  can  remember  them,"  said  O'Rourke.  "It's  just  as  easy 
as  remembering  4-11-44." 

"Yes,  and  much  more  useful,"  said  the  instructor. 

"It  is  also  quite  important  for  you  to  know  how  to  find 
the  volume  and  area  of  a  cylinder.  For  example,  if  you  are 
going  to  cover  a  tank  with  asbestos,  you  would  want  to  know 
how  to  find  the  total  area.  A  cylinder,  you  know,  is  a  figure 
which  if  cut  across  perpendicular  to  its  axis  at  any  point 


EXAMINATION    QUESTIONS    AND   ANSWERS  199 

beteween  the  top  and  bottom  will  be  circular  in  section. 
Hence  if  we  have  a  cylindrical  tank  5  feet  in  diameter  and 
10  feet  high,  and  wanted  to  know  how  much  material  was 
needed  to  cover  it  all  over,  we  would  first  find  the  circum- 
ference of  a  circle  5  feet  in  diameter,  which  is  5  X  3.1416  = 
15.708  feet.  Multiply  this  by  the  height,  10  feet,  and  we  have 
10  X  15708  =  157.08  square  feet  to  cover  all  around  the 
sides. 

"How  would  you  find  the  amount  of  covering  for  the  ends, 
O'Rourke?" 

"Multiply  her  by  .7854,"  replied  the  young  man. 

"Multiply  what?" 

"Why,  the  5  feet  diameter,  of  course,"  confidently  said 
O'Rourke. 

"There's  where  you're  wrong,  as  usual.  I  told  you  that  in 
order  to  find  the  area  of  a  circle  you  must  square  the  diam- 
eter. So  we  have  5  X  5  =  25  and  25  X  -7^54  =  19.635  square 
feet  as  the  area  of  one  end.  But  there  are  two  ends,  so  we 
must  allow  for  twice  that,  or  39.27  square  feet.  This  added 
to  157.08  gives  us  196.35  square  feet  as  the  total  surface  of 
the  tank. 

"It  is  of  equal  importance  for  you  to  be  able  to  find  the 
volume  of  a  cylinder,  or  how  much  it  will  hold  if  it  is 
hollow,  or  how  large  it  is  if  solid.  For  example,  we  want  to 
know  how  many  gallons  of  oil  or  water  a  tank  like  the  above 
will  hold.  To  do  this  we  must  first  find  the  area  of  the 
circle,  which  from  the  above  we  know  to  be  19.635  square 
feet,  and  as  it  is  simpler  to  calculate  it  in  inches  we  multiply 
this  number  by  144,  or  19.635  X  144  —  2827.4  square  inches. 
Right  here  I  want  to  warn  you  against  a  mistake  that  so 
many  beginners  fall  into;  that  is,  of  multiplying  feet  by 
inches.  Remember,  feet  must  always  be  multiplied  by  feet 
and  inches  by  inches,  or  your  answer  will  be  wrong.  Hence 
the  height  or  depth  of  this  tank  being  10  feet,  we  must  use 


2OO  MC  ANDREWS    FLOATING    SCHOOL 

10  X  12,  or  120  inches,  as  the  multiplier.  Then  we  have 
28274  X  I2o  =  339,288  cubic  inches  as  the  volume  of  the 
tank.  There  are  231  cubic  inches  in  a  gallon,  so  we  divide  the 
total  number  of  cubic  inches  in  the  tank,  339,288  by  231,  and 
we  find  in  even  numbers  that  the  tank  will  contain  1,469 
gallons. 

"There  are  not  many  spherical  surfaces  around  marine 
machinery,  but  it  might  be  useful  at  some  time  for  you  to 
know  how  to  find  the  volume  and  surface  of  a  sphere  or  ball. 
This  is  defined  as  a  solid  bounded  by  a  curved  surface,  every 
point  of  which  is  equally  distant  from  a  point  within  known 
as  the  center.  Any  line  through  the  center  and  cutting  the 
surface  is  the  diameter.  We  will  suppose  that  we  have  a  ball 
float  in  the  feed  tank  12  inches  in  diameter,  and  want  to  know 
how  much  sheet  copper  it  will  take  to  make  such  a  float.  The 
rule  is  to  square  the  diameter  and  multiply  by  our  old  friend 
3.1416.  Thus  12  X  12  =  144  and  144  X  3-14*6  =  452.39 
square  inches  as  the  surface  of  the  ball.  Now  if  we  had  a 
cast  iron  ball  6  inches  in  diameter  hanging  on  a  safety  valve 
lever,  and  wanted  to  know  its  weight,  we  would  first  find  its 
volume  in  cubic  inches.  To  do  this  the  rule  is  to  cube  the 
diameter;  that  is,  multiply  it  by  itself  twice,  and  multiply 
that  product  by  .5236.  Thus  in  this  case  it  would  be 
6X6X6  =  216,  and  216  X  -5236  =  113.1  cubic  inches  in 
the  ball.  Knowing  that  cast  iron  weighs  .26  pound  to  the 
cubic  inch  we  multiply  113.1  by  .26,  and  find  that  the  ball 
weighs  29.41  pounds." 

"Chief,  could  you  use  that  rule  to  find  the  weight  of  a 
highball  ?"  inquired  O'Rourke. 

"From  all  I  can  hear  of  the  subject  highballs  haven't  much 
weight,  as  their  general  tendency  is  to  make  you  light-headed," 
suggested  McAndrew. 


EXAMINATION  QUESTIONS  AND  ANSWERS  201 

SAFETY  VALVE  PROBLEMS 

"Now  we  are  ready  for  the  all-important  safety  valve 
problem,  and  I  am  particularly  anxious  to  have  you  under- 
stand the  principle  upon  which  it  is  worked,  rather  than  to 
learn  some  particular  example,  as  is  too  often  the  case  with 
beginners.  When  you  come  up  for  examination  you  will  find 
that  the  conditions  given  you  will  be  entirely  different  from 
any  problem  you  may  have  worked  out.  The  following  is  an 
outline  sketch,  which  will  enable  you  to  follow  out  the 
principle  involved. 

"In  Fig.  37,  O  represents  the  fulcrum,  or  point  where  the 
lever  is  hinged;  V  represents  the  valve;  N  the  center  of 


1 


ftr 


FIG.  37. SAFTETY  VALVE  PROBLEM 

gravity  of  the  lever ;  that  is  the  point  where,  if  the  lever 
should  be  picked  up  in  your  hand,  it  would  exactly  balance 
and  remain  in  a  horizontal  position.  M  represents  the  point 
where  the  weight  W  is  located  on  the  lever.  The  forces  act- 
ing on  the  lever  at  M  and  N  have  a  tendency  to  make  it  fall 
or  rotate  in  a  direction  opposite  to  the  hands  of  a  watch. 
The  weight  of  the  valve  and  stem  at  S  also  has  that  ten- 
dency. The  only  upward  force,  or  the  only  force  tending 
to  make  the  lever  turn  in  the  same  direction  as  the  hands  of 
a  watch,  is  the  pressure  of  the  steam  on  the  valve  V ,  operating 
on  the  lever  at  the  point  S.  Now,  safety  valve  levers  are  not 
supposed  to  be  rotating  in  either  direction,  but  to  remain  in 
equilibrium,  hence  the  downward  forces  must  be  such  as  to 
balance  the  upward  force,  and  the  only  force  that  can  be 


2O2  MCA^REW'S   FLOATING    SCHOOL 

adjusted  to  bring  them  all  in  equilibrium  is  that  of  the  weight 
W.  This  can  be  done  either  by  varying  the  weight  itself  or 
by  moving  it  out  or  in  from  the  fulcrum  O. 

"The  tendency  to  cause  the  lever  to  rotate  about  the  ful- 
crum, with  a  ball  of  a  given  weight,  varies  with  the  distance 
the  ball  is  from  the  fulcrum  exactly  as  the  principle  of  the 
levers,  which  I  have  explained  to  you  before.  To  measure 
this  tendency  you  multiply  the  weight  by  the  distance  from 
the  fulcrum,  and  the  product  is  known  as  the  moment.  Thus 
a  weight  of  i  pound,  placed  4  feet  from  the  fulcrum,  would 
have  a  moment  of  4  foot-pounds  to  cause  rotation.  Similarly, 
a  weight  of  4  pounds  placed  only  i  foot  from  the  fulcrum 
would  have  the  same  moment  of  4  foot-pounds.  If  the  dis- 
tances were  given  in  inches  we  would  speak  of  the  moments 
in  so  many  inch-pounds. 

"To  illustrate  these  principles,  suppose  in  Fig.  37  we  were 
given  the  following  quantities : 

Distance  OS  from  fulcrum  to  center  of  valve  6  inches. 

Weight  of  valve  and  stem  8  pounds. 

Diameter  of  the  safety  valve  3  inches. 

Steam  pressure  50  pounds. 

Weight  of  lever  10  pounds. 

Center  of  gravity  of  lever  20  inches  from  fulcrum. 

Distance  of  weight  (OM)  from  fulcrum  30  inches. 

Required,  the  size  of  the  weight  necessary  to  keep  the 
valve  in  equilibrium  when  steam  is  at  50  pounds 
pressure. 

"The  upward  tendency  is  represented  by  the  pressure  of 
the  steam  at  S.  A  valve  3  inches  in  diameter  has  an  area  of 
7.07  square  inches ;  this,  multiplied  by  50,  the  pressure  per 
square  inch,  gives  us  a  total  upward  pressure  of  353.5  pounds. 
But  this  is  6  inches  from  the  fulcrum,  so  the  moment  will  be 
353-5  X  6  =  2,121.0  inch-pounds. 

"All  the  other  weights  exert  downward  forces  and  tend  to 


EXAMINATION    QUESTIONS    AND   ANSWERS  2O3 

affect  this  upward  pressure,  so  we  will  have  the  following  to 
work  against  the  2,121  inch-pounds  moment  of  the  valve. 

"Weight  of  valve  and  stem  (8  pounds)  multiplied  by  lever 
arms  (6  inches)  equals  48  inch-pounds. 

"Weight  of  lever  (10  pounds)  multiplied  by  distance  OAr 
(20  inches)  equals  200  inch-pounds. 

"We  do  not  yet  know  the  size  of  the  weight  W ,  but  we 
do  know  its  distance  from  the  fulcrum  (30  inches),  hence  we 
add  48  and  200,  and  find  the  sum  to  be  248,  and  subtract  it 
from  2,121  and  find  we  have  1,873  inch-pounds  to  make  the 
downward  moments  equal  to  the  upward  moments.  This 
1,873  is  in  inch-pounds,  hence  dividing  it  by  30  inches  will  give 
us  62.4  pounds  as  the  size  of  the  weight  to  maintain  the 
balance. 

"We  will  suppose  that  the  weight  (62.4)  had  been  given  us, 
and  we  were  asked  to  ascertain  what  distance  it  should  be 
located  from  the  fulcrum  in  order  to  balance  50  pounds  pres- 
sure on  the  valve.  In  this  case  we  would  have  the  same 
upward  pressure  from  the  valve,  or  353.5  pounds,  and  the 
moment  of  2,121.0  inch-pounds.  The  downward  forces  for  the 
weights  of  the  valve  and  stem  and  the  lever  will  be  repre- 
sented by  a  total  of  248  inch-pounds.  As  before,  subtract 
this  from  2,121  and  we  have  1,873  inch-pounds.  Knowing  the 
size  of  the  weight  in  pounds  (62.4)  we  divide  it  into  1,873, 
and  find  that  the  weight  should  be  located  30  inches  from  the 
fulcrum  in  order  to  be  in  balance. 

"Another  way  the  problem  might  be  given  you  is  to  find 
out  what  the  steam  pressure  would  be  with  all  the  conditions 
given  as  above.  The  downward  pressures  would  be  as  before : 

Inch-Pounds 

Valve  and  stem,  8  pounds  X  6  inches        =       48 
Lever,  10  pounds  X  20  inches  =     200 

Weight,  62.4  pounds  X  30  inches  =  1,873 

Total.      2,121 


2O4  MC  ANDREW'S  FLOATING  SCHOOL 

"We  know  that  the  area  of  the  valve  is  7.07  square  inches, 
and  its  lever  arm,  or  distance  from  the  fulcrum,  is  6  inches, 
so  we  have  7.07  X  6  —  42.42.  As  there  is  only  the  one  force 
acting  upward  we  divide  2,121  by  42.42,  and  find  that  a  pres- 
sure of  50  pounds  can  be  carried  with  the  weight  set  in  the 
position  given. 

How  TO  FIGURE  THE  STRESSES  ON   BOILER  BRACES 
"The  next  problem  we  will  take  up  is  the  one  required  by 
law:    'to  figure  and    determine   the    stresses   brought   on   the 
braces  of  a  boiler  with  a  given  pressure  of  steam,  the  position 
and  distance  apart  of  braces  being  known.' 

"This  is  very  simple,  as  it  only  involves  multiplication. 
Thus  if  the  braces  are  spaced  12  inches  apart  each  way,  and 
the  steam  pressure  is  160  pounds  per  square  inch,  we  multiply 
12  by  12,  and  find  that  there  are  144  square  inches  to  be  sup- 
ported, and  144  X  ico  =  23,040  pounds  stress  which  is  brought 
on  one  brace.  Similarly,  if  the  braces  are  spaced  14  inches 
apart  horizontally  and  10  inches  vertically,  and  the  steam 
pressure  is  160  pounds  per  square  inch,  we  would  multiply 
14  by  10,  and  find  that  there  is  an  area  of  140  square  inches 
to  be  supported  by  one  brace,  and  140  X  160  would  give  us 
22,400  pounds,  or  an  even  10  tons,  as  the  total  stress  on  one 
brace. 

"The  inspectors,  however,  do  not  confine  themselves  to  this 
simple  form  of  the  problem,  and  you  are  liable  to  get  one 
like  the  above,  with  the  addition  that  they  would  ask  you  the 
safe  diameter  of  the  brace.  To  perform  this  we  must  know 
the  United  States  rules  as  to  the  safe  working  load  per 
square  inch  of  section.  These  rules  give  allowances  of  6,000 
pounds  per  square  inch  of  section  for  iron ;  above  5  square 
inches  sectional  area  if  steel  is  used  and  regularly  inspected 
an  allowance  of  8,000  pounds  per  square  inch  is  made;  braces 
above  il/4  inches  diameter  are  not  allowed  to  exceed  9,000 


EXAMINATION    QUESTIONS    AND   ANSWERS  20$ 

pounds    per    square    inch    of    section   if    such    stays    are    not 
forged  or  welded. 

"You  might  get  a  question  similar  to  the  following:  What 
diameter  of  bracing  should  be  used  to  support  a  flat  surface 
12  inches  by  12  inches,  using  steam  at  200  pounds  pressure? 
The  solution  would  be  12  X  12  =  144,  and  144  X  200  = 
28,800  pounds  to  be  supported;  28,800  -4-  9,000  =  3.2  square 
inches.  Looking  at  a  table  of  areas  we  would  find  that  a  stay 
having  a  diameter  of  2  1/16  inches  has  an  area  of  3.341  square 
inches,  which  is  the  nearest  area  to  the  one  we  know  to  be 
necessary.  Very  likely  these  braces  would  be  made  2l/% 
inches  in  diameter,  as  that  would  be  the  nearest  commercial 
size  obtainable. 

ALLOWABLE  WORKING  PRESSURE  ON  A  BOILER 
"Possibly  you  will  be  asked  how  to  find  what  pressure  will 
be  allowable  on  a  Scotch  boiler,  knowing  the  thickness  of 
shell,  the  diameter  of  the  boiler,  tensile  strength  of  plate,  etc. 
"The  United  States  Government  rule  is  to  multiply  one- 
sixth  of  the  lowest  tensile  strength  in  pounds  by  the  thick- 
ness in  inches,  and  divide  by  one-half  the  diameter,  also  in 
inches ;  20  percentum  is  to  be  added  if  double  riveting  is  used 
for  the  horizontal  seams,  which,  of  course,  would  be  used 
these  days ;  in  fact,  the  seams  would  probably  be  triple- 
riveted,  but  the  rule  makes  no  allowance  for  that. 

"For  example,  if  we  had  a  boiler  15  feet  in  diameter,  made 
of    steel    plates,    the   lowest    tensile    strength    of    which    was 
Co,ooo  pounds  per  square  inch,  and  the  shell  was  il/2  inches 
In  thickness,  and  we  wanted  to  find  what  presure  would  be 
allowed  by  the  inspectors,  we  would  proceed  as  follows : 
15  feet  X  12  =  180  inches  diameter. 
One-half  of  180  =  90  inches. 

One-sixth  of  the  lowest  tensile  strength  (60,000 pounds) 
=  io,oco  pounds. 


2o6  MC  ANDREW'S  FLOATING  SCHOOL 

i}/2  inches  =1.5  inches. 
10,000  X  1.5  =  15,000. 
15,000  -=-  90  =  166.6  pounds. 

"As  double  riveting  allowances  must  be  made,  we  add  20 
percent  of  this  and  have  166.6  -f-  33.4  =  200  pounds  pressure 
allowable  on  the  boiler." 

"Chief,"  said  Pierce,  "suppose  we  wanted  to  find  out  what 
thickness  to  make  this  boiler  shell,  and  we  knew  the  size  and 
pressure  we  wanted  to  carry?" 

"We  would  simply  reverse  the  operation,"  replied 
McAndrew.  "In  other  words,  multiply  the  radius  in  inches 
by  the  pressure  in  pounds  and  divide  by  one-sixth  the  tensile 
strength.  Thus  90  X  200  =  18,000;  18,000  -f-  15,000  =  1.2 
inches  thick.  But  for  double  riveting  an  allowance  of  20 
percent  additional  is  made,  and  1.2  is  only  80  percent 
(100  —  20)  of  the  thickness  allowance.  As  80  percent  is  1.2, 
100  percent  will  be  1.5  inches,  the  thickness  which  we  will 
have  to  make  the  boiler  shell  in  order  to  withstand  the.  pres- 
sure required  and  conform  to  the  rules. 

"Strange  to  say,  all  the  problems  required  by  law  to  be 
given  candidates  for  engineers'  licenses  in  this  country  relate 
to  boilers.  These  laws  were  passed  in  the  early  days  of  steam 
navigation,  and  I  presume  that  the  legislators  in  those  days 
thought  that  if  a  man  understood  boilers  thoroughly  he  could 
manage  somehow  to  run  the  engines.  Fortunately  for  the 
good  of  the  service  the  inspectors  ask  questions  concerning 
nearly  all  parts  of  the  steam  machinery,  so  it  is  well  to  be 
prepared  in  a  general  way." 

"Why  can't  we  get  some  of  the  old  examination  papers?" 
observed  Nelson. 

"Just  try  it  for  yourself  and  see,"  said  McAndrew.  "In 
the  first  place  they  are  not  published,  so  it  is  not  necessary 
to  give  any  other  reasons. 

"I  have,  however,  put  down  in  my  notebook  a  number  of 


EXAMINATION    QUESTIONS    AND    ANSWERS  2O7 

the  questions  that  were  asked  me  on  my  different  examina- 
tions, and  I  will  give  you  the  benefit  of  some  of  those  I  have 
had,  and  also  of  some  of  those  I  have  obtained  from  other 
engineers.  They  are  as  follows: 

QUESTIONS  AND  ANSWERS  FROM   MARINE  ENGINEERS' 
EXAMINATION   PAPERS 

Q.  What  is  the  advantage  of  a  triple-expansion  engine  over 
a  compound ;  how  is  the  power  divided ;  how  can  you  tell 
when  the  power  is  equally  divided? 

A.  Greater  economy,  due  to  a  greater  degree  of  expansion 
of  the  steam ;  the  power  should  be  divided  as  nearly  equally 
as  possible  between  the  three  cylinders ;  the  only  way  to  ascer- 
tain whether  the  division  is  equal  or  not  is  to  take  a  set  of 
cards  from  each  cylinder  and  calculate  the  horsepower  which 
each  develops. 

Q.  What  are  the  principal  types  of  condensers? 

A.  Jet  and  surface. 

Q.  What  are  the  necessary  appliances  for  operating  a  sur- 
face condenser? 

A.  The  circulating  pumps  for  forcing  the  cooling  water 
through  the  tubes,  and  the  air  pump  for  pumping  out  the 
condensed  water  and  the  vapor  from  the  interior  of  the 
condenser. 

Q.  How  would  you  ascertain  if  a  condenser  was  leaking 
salt  water? 

A.  By  taking  off  the  water  chest  at  each  end  and  filling 
the  condenser  with  fresh  water.  If  any  water  runs  out 
through  the  ends  of  the  tubes  there  are  leaks  in  the  tubes, 
which,  when  the  condenser  is  in  operation,  would  admit  salt 
water  to  the  condenser. 

Q.  How  many  sets  of  valves  are  there  in  an  air  pump; 
which  set  could  be  dispensed  with  and  the  pump  continue  to 
work? 


2o8  MC  ANDREW'S  FLOATING  SCHOOL 

A.  The  valves  are  known  as  foot  valves,  bucket  valves  and 
discharge  valves.  The  pump  could  run  without  foot  valves, 
but  it  works  better  with  them. 

Q.  What  is  a  vacuum  ? 

A.  A  vacuum  means  absence  of  air. 

Q.  What  is  steam? 

A.  Steam  is  a  thin,  invisible,  elastic  vapor  formed  by  the 
application  of  heat  to  water. 

Q.  Is  it  possible  to  get  a  perfect  vacuum? 

A.  It  is  not. 

Q.  If  a  vacuum  gage  shows  24  inches,  how  many  pounds 
pressure  does  that  indicate? 

A.  About  12  pounds. 

Q.  Suppose  the  steam  gage  shows  60  pounds  and  the 
vacuum  gage  24  inches,  what  would  be  the  pressure  in  pounds 
per  square  inch  on  the  piston? 

A.  One-half  of  24  inches  means  a  pressure  of  12  pounds, 
so  the  pressure  per  square  inch  on  the  piston  would  be  60  + 
12  =  72  pounds. 

Q.  What  is  the  duty  of  a  condenser? 

A.  A  condenser  serves  the  purpose  of  condensing  or  turn- 
ing the  exhaust  steam  back  into  its  original  state  as  water;  in 
this  operation  a  vacuum  is  formed  which  increases  the  power 
of  the  engine  by  carrying  out  the  expansion  of  the  steam  to 
nearly  its  limit. 

Q.  How  does  a  leaky  condenser  affect  a  boiler? 

A.  It  allows  salt  water  to  be  fed  to  the  boiler,  and  if  the 
leak  is  extensive  it  will  cause  too  great  a  quantity  of  water 
to  accumulate  in  the  boiler,  so  that  the  boiler  will  have  to  be 
blown  down  at  intervals. 

Q.  Describe  the  course  of  steam  from  the  boiler  to  a  triple- 
expansion  engine,  naming  the  valves  and  pipes,  etc.,  it  passes 
through  until  in  the  form  of  water  it  reaches  the  feed  tank? 

A.  The  steam  after  being  formed  in  the  boiler  first  passes 


EXAMINATION    QUESTIONS    AND   ANSWERS  2OO, 

through  the  dry-pipe,  the  object  of  which  is  to  keep  the  water 
out  of  the  steam.  It  then  passes  through  the  main  stop  valve 
on  the  boiler  into  the  main  steam  pipe.  In  the  main  steam 
pipe  is  sometimes  fitted  a  separator  which  removes  the  water 
from  the  steam.  Passing  through  the  throttle  valve  it  enters 
the  high-pressure  steam  chest,  thence  through  the  high- 
pressure  valve  into  the  high-pressure  cylinder ;  after  a  certain 
degree  of  expansion  in  that  cylinder  it  is  exhausted  into  the 
first  receiver,  and  passing  through  the  intermediate  valve  it 
enters  the  intermediate  cylinder,  where  another  degree  of 
expansion  ensues.  It  is  exhausted  from  the  intermediate 
cylinder  into  the  second  receiver,  and  thence  through  the  low- 
pressure  valve  into  the  low-pressure  cylinder,  where  it  is 
expanded  to  its  final  stage  and  then  is  exhausted  into  the 
condenser.  There  it  is  transformed  into  water  by  coming  in 
contact  with  the  surface  of  the  cold  tubes.  This  water  is 
pumped  out  of  the  bottom  of  the  condenser  by  means  of  the 
air  pump,  and  is  discharged  into  the  feed  tank,  whence 
it  is  again  pumped  into  the  boilers  by  means  of  the  feed 
pump. 

Q.  Where  should  the  throw  of  the  eccentric  be  placed  in 
relation  to  the  crank  of  a  slide  valve  engine? 

A.  It  should  be  set  ahead  of  the  crank  where  the  steam  is 
taken  on  the  outside  of  the  valve. 

Q.  How  would  you  set  an  eccentric  on  a  new  shaft  to  have 
the  valve  properly  set? 

A.  Ninety  degrees  ahead  of  the  crank,  plus  the  amount  of 
the  lap,  plus  the  amount  of  the  lead.  Before  setting  the 
eccentric  you  should  lock  it  with  a  set  screw,  and  then  by 
turning  the  engine  around  one  revolution  see  that  the  lead  is 
correct  for  both  ends.  After  it  is  found  to  be  in  the  correct 
position  then  mark  and  cut  the  keyway  in  the  shaft. 

Q.  What  is  meant  by  lap? 

A.  The  amount  a  slide  valve  overlaps  the  steam  port,  when 


210  MC  ANDREW'S  FLOATING  SCHOOL 

it  is  in  mid-position,  if  it  is  on  the  steam  side.  On  the  exhaust 
side  it  is  the  amount  it  overlaps  the  exhaust  side.  The  former 
is  used  for  regulating  the  cut-off  and  the  latter  to  provide 
compression  at  each  end  of  the  stroke. 

Q.  What  is  meant  by  lead  ? 

A.  By  lead  is  meant  the  amount  the  valve  is  open  when  the 
piston  is  at  the  end  of  its  stroke.  Lead  is  given  to  admit 
steam  before  the  piston  reaches  the  end  of  the  stroke,  and  to 
start  it  off  promptly  on  the  new  stroke. 

Q.  Can  steam  be  cut  off  equally  in  the  two  ends  of  a  cylin- 
der when  using  a  lap  valve? 

A.  No,  it  cannot,  for  the  reason  that  the  crank  is  not  hori- 
zontal when  the  piston  is  at  half  stroke,  but  a  little  above  the 
center,  due  to  the  angularity  of  the  connecting  rod.  When 
the  crank  is  horizontal  the  piston  is  a  little  below  the  center 
of  its  stroke,  therefore  the  steam  follows  further  on  the  top. 

Q.  Is  the  lead  increased  or  decreased  by  shifting  the  link 
to  mid-position? 

A.  If  you  have  "open"  rods  the  lead  will  increase  as  we 
run  in  the  links,  and  we  shorten  the  point  of  cut-off.  If  the 
rods  are  crossed  the  opposite  is  the  case. 

Q.  What  are  the  practical  limits  of  cutting  off  with  a  slide 
valve  ? 

A.  It  is  not  practicable  to  cut  off  very  short  with  a  lap 
valve,  on  account  of  the  excessive  lap  necessary  and  the  in- 
creased travel  of  the  valve.  Generally  speaking,  it  is  inad- 
visable to  cut  off  at  less  than  ^  the  stroke,  nor  more  than  %. 

Q.  What  is  the  difference  in  the  throw  of  an  eccentric  of  a 
double-ported  valve  from  that  necessary  for  a  single-ported 
valve  ? 

A.  Double-ported  valves  are  used  to  reduce  the  travel  of  a 
valve  by  giving  a  double  admission  at  each  end,  hence  the 
travel  is  only  one-half  that  of  a  single-ported  valve. 


EXAMINATION    QUESTIONS    AND    ANSWERS  211 

Q.  Find  the  area  of  opening  in  a  boiler  shell  for  a  duplex 
safety  valve,  each  valve  being  3^  inches  diameter. 

A.  3-5  X  3-5  =  12.25,  this  multiplied  by  .7854  =  9.62  as  the 
area  of  one  valve ;  9.62  X  2  =  19.24  as  the  area  of  the  hole 
in  the  boiler.  The  diameter  corresponding  to  that  area  is 
practically  5  inches. 

Q.  What  is  meant  by  foaming  or  priming?  How  do  you 
explain  the  cause? 

A.  "Foaming"  is  the  violent  boiling  or  ebullition  of  the 
water  in  the  boiler,  the  water  level  rises  and  falls  rapidly,  and 
water  gets  mixed  with  the  steam  and  is  carried  to  the  engine; 
this  latter  action  is  known  as  "priming."  Foaming  is  liable  to 
occur  when  the  boiler  is  dirty;  when  the  boiler  is  forced  to  a 
great  extent;  when  changing  from  salt  to  fresh  feed;  when 
too  much  soda  is  used  in  the  boiler,  or  if  the  boiler  does  not 
have  sufficient  steam  space. 

Q.  How  would  you  check  "foaming"? 

A.  Slow  down  the  engine ;  put  on  a  strong  feed ;  pump  and 
blow  if  necessary. 

Q.  What  precautions  are  necessary  when  the  boiler  is 
priming? 

A.  Open  all  cylinder  and  valve  chest  drains,  and  if  neces- 
sary slow  down  the  engine. 

Q.  What  are  the  bad  effects  of  oil  or  grease  getting  into  the 
boilers? 

A.  The  oil  forms  a  scum  on  the  surface  of  the  water  in  the 
boiler,  and  gradually  collects  together  with  particles  of  salt 
scales,  sulphate  of  lime,  etc.,  and  will  finally  settle  on  the 
tubes  or  on  the  furnace  crowns.  Being  a  very  poor  conductor 
of  heat  it  is  liable  to  cause  the  metal  to  become  overheated, 
with  consequent  collapse  or  bulging  of  the  furnaces.  The  oil 
will  also  become  decomposed,  form  acids  and  expedite  elec- 
trolytic action,  with  its  consequent  pitting  of  the  steel  plates 
and  tubes. 


212  MC  ANDREWS    FLOATING    SCHOOL 

Q.  What  density  would  you  carry  the  water  in  the  boiler, 
using  a  high-pressure  of  steam,  such  as  180  pounds? 

A.  With  steam  at  that  pressure  allow  the  density  to  rbe  as 
high  as  4  or  4^2  thirty-seconds  before  blowing,  as  with  high 
temperature  if  we  keep  blowing  to  hold  the  density  low,  we 
increase  the  scale  as  the  calcium  sulphate  in  the  sea  water 
deposits  at  the  comparatively  low  temperature  of  290  de- 
grees F. 

Q.  How  would  you  determine  the  density  of  boiler  water 
if  the  salinometer  was  out  of  order? 

A.  By  means  of  noting  the  boiling  point.  Fresh  water  boils 
at  212  degrees  F.  under  atmospheric  pressure  only.  Ordinary 
sea  water  boils  at  213.2  degrees  F.  At  a  density  of  2  thirty- 
seconds  it  boils  at  214.2  degrees  F.,  and  so  on. 

Q.  How  high  should  the  water  be  carried  over  the  tops  of 
combustion  chambers? 

A.  Not  less  than  6  inches. 

Q.  Describe  a  fusible  plug.  Where  are  they  placed  in  a 
boiler?  and  for  what  purpose?  What  materials  are  used  in 
their  construction? 

A.  A  fusible  plug  is  usually  made  of  brass,  filled  with  Banca 
tin.  They  are  to  relieve  the  pressure  in  case  of  low  water 
in  the  boiler,  the  theory  being  that  the  tin  will  melt  out  when 
there  is  no  water  over  it,  and  allow  the  steam  to  blow  through 
the  hole  thus  formed.  In  boilers  having  combustion  chambers 
they  must  be  placed  in  the  top,  or  the  highest  heating  surface. 
In  flue  boilers  one  must  be  placed  in  each  flue  and  one  in  the 
shell  of  the  boiler  from  the  inside  just  below  the  fire  line,  and 
not  less  than  4  feet  from  the  forward  end  of  the  boiler. 

Q.  Where  would  you  use  a  soft  patch  on  a  boiler,  and  how 
should  it  be  applied? 

A.  A  soft  patch  should  be  used  over  a  weak  spot  on  the 
boiler,  or  over  a  part  of  a  joint  where  the  rivets  are  cor- 
roded away  and  leaking.  It  should  never  be  used  where  it 


EXAMINATION    QUESTIONS    AND   ANSWERS  213 

will  come  in  contact  with  the  fire  or  flames.  It  is  usual  to 
make  them  of  3/i6-inch  or  ^-inch  plate,  and  of  a  size  suf- 
ficient to  overlap  all  portions  of  the  weak  spot  to  be  patched. 
A  templet  of  lead  should  be  made  for  the  patch.  The  patch 
itself  should  be  made  to  correspond  to  the  templet;  it  should 
be  lipped  around  its  edges,  so  as  to  hold  the  putty  of  red  lead 
and  iron  filings.  Each  bolt  should  be  fitted  with  washers  and 
grommets  of  asbestos  thread  rubbed  down  with  white  lead. 
Bake  the  patch  with  heated  irons  and  set  up  as  tightly  on  the 
bolts  as  possible. 

Q.  Where  on  a  boiler  would  you  use  a  hard  patch,  and  how 
should  it  be  applied  ? 

A.  A  hard  patch  is  used  for  a  permanent  job,  and  can  be 
fitted  over  a  hole  or  defective  part  of  the  boiler,  even  if  it 
does  come  in  contact  with  the  fire.  The  defective  part  should 
be  cut  out,  a  templet  made  large  enough  to  allow  for  a  riveted 
joint  all  around  the  hole.  The  holes  should  be  drilled  from 
the  templet,  and  when  all  is  ready  drive  the  rivets  and  calk 
the  edges  all  around  the  same  as  in  regular  boiler  con- 
struction. 

Q.  Upon  what  does  the  strength  of  a  cylindrical  boiler 
depend  ? 

A.  Upon  the  thicknes  of  the  shell. 

Q.  Why  are  two  safety  valves  used  instead  of  one? 

A.  The  combined  area  of  the  two  valves  must  be  equal  to 
the  area  of  one  valve,  as  required  by  the  rules  of  the  Steam- 
boat Inspection  Service.  When  two  valves  are  used  there  is 
less  likelihood  of  both  getting  out  of  order  than  would  be  the 
case  if  only  one  is  used. 

Q.  What  should  be  the  angle  of  the  seat  of  safety  valves? 

A.  The  seats  should  have  an  angle  of  inclination  of  45 
degrees  to  the  center  line  of  their  axes. 

Q.  What  determines  the  size  of  safety  valves  of  different 
kinds? 


214  MC  ANDREW'S  FLOATING  SCHOOL 

A.  Lever  safety  valves  must  have  an  area  of  not  less  than 
I  square  inch  to  2  square  feet  of  the  grate  surface.  Spring 
loaded  safety  valves  must  have  an  area  of  not  less  than  i 
square  inch  for  each  3  square  feet  of  grate  surface,  except  for 
watertube  boilers  carrying  a  steam  pressure  exceeding  175^ 
pounds  per  square  inch,  when  they  are  required  to  have  an 
area  of  not  less  than  I  square  inch  for  each  6  square  feet  of 
grate  surface. 

Q.  Name  all  the  valves  on  a  boiler,  stating  the  most  im- 
portant one  and  where  it  is  placed. 

A.  The  valves  on  a  marine  boiler  are  the  safety  valve, 
main  stop  valve,  auxiliary  stop  valve,  main  feed  check  valve, 
auxiliary  feed  check  valve,  surface  blow  valve,  bottom  blow 
valve,  drain  valve  and  sometimes  a  sentinel  valve. 

The  most  important  one  is  the  safety  valve,  which  is  placed 
on  the  shell  at  the  highest  part  of  the  boiler. 

Q.  What  would  be  the  result  if  both  feed  valves  were  shut 
on  a  boiler  and  the  engine  was  in  motion  at  full  speed? 

A.  The  water  in  the  boiler  would  be  gradually  used  up,  and 
if  not  replenished  the  boiler  would  explode. 

Q.  Does  the  water  in  the  glass  always  show  the  true  level 
in  the  boiler? 

A.  No,  it  does  not.  Occasionally  the  pipes  leading  to  the 
gage  glass  may  become  choked  up  with  hardened  oil,  or  the 
valves  may  not  be  opened.  These  should  be  frequently  tried 
to  see  that  they  are  kept  open. 

Q.  A  ship  has  six  double-ended  boilers  with  six  furnaces, 
each  of  which  is  6  feet  6  inches  long  by  3  feet  3  inches  in 
diameter,  and  when  the  ship  is  making  15  knots  there  is 
15  pounds  of  coal  burned  per  square  foot  of  grate  area  per 
hour.  How  many  tons  of  coal  would  be  required  for  a  voyage 
of  3,000  miles,  and  how  many  tons  would  be  burned  each  day  ? 

A.  As  each  furnace  is  6^2  feet  long  and  3*4  feet  in  diam- 
eter, there  would  be  &/2  X  3/4  =  21$^  square  feet  in  each 


EXAMINATION    QUESTIONS    AND  ANSWERS  215 

furnace;  21 1/&  X  6  =  126^4  square  feet  of  grate  surface  in 
each  boiler ;  12624  X  6  —  760^  square  feet  of  grate  surface 
in  all  the  boilers;  760^  X  15  =  HA^7l/2  pounds,  or  5.09  tons 
of  coal  burned  per  hour;  3,000  -=-  15  =  200  hours'  time  to 
make  the  voyage  of  3,006  miles ;  5.09  X  200  =  1,018  tons  to 
make  the  voyage  of  3,000  miles;  5.09  X  24  =  122.16  tons 
burned  each  day. 

Q.  If  you  were  in  charge  of  a  modern  triple-expansion 
engine,  and  the  intermediate  connecting  rod  broke  beyond 
repair,  what  would  you  do? 

A.  Disconnect  the  rod  at  both  ends;  take  out  the  inter- 
mediate valve,  so  as  to  allow  the  steam  to  pass  from  the 
high-pressure  exhaust  direct  to  the  low-pressure  valve  chest 
and  proceed  on  the  voyage,  using  only  the  high  and  low- 
pressure  cylinders. 

Q.  How  long  would  you  run  a  boiler  if  you  had  used  only 
fresh  water  as  feed  before  cleaning  it? 

A.  About  700  steaming  hours  with  the  main  engine  in  use 
would  be  about  the  safe  limit  before  opening  the  boiler  to 
clean  it,  as  it  will  be  found  at  the  end  of  that  time  that  the 
zincs  will  need  renewing. 

Q.  If  the  high-pressure  valve  stem  broke  beyond  repair 
what  would  you  do? 

A.  Take  out  the  high-pressure  valve  and  let  the  live  steam 
from  the  boilers  blow  directly  through  to  the  intermediate 
valve  chest,  and  run  the  engine  compound  with  the  inter- 
mediate and  low-pressure  cylinders. 

Q.  How  many  gallons  of  water  is  pumped  per  hour  by  a 
single-acting  plunger  pump,  whose  diameter  is  6  inches,  stroke 
IO  inches,  and  making  60  strokes  per  minute? 

A.  The  area  corresponding  to  a  diameter  of  6  inches  is 
28.27  square  inches.  This  is  found  by  multiplying  6x6  = 
36  X  7854  =  28.27  square  inches.  Now  28.27  X  10  inches  = 
282.7  cubic  inches  per  stroke;  282.7  X  60  =  16,962  cubic 


216  MC  ANDREW'S  FLOATING  SCHOOL 

inches  per  hour;  16,962  ~  231  (number  of  cubic  inches  per 
gallon)  =  73.4  gallons  per  minute ;  734  X  60  —  4404  gallons 
per  hour. 

Q.  What  are  the  principal  things  to  look  after  upon  taking 
charge  of  a  watch? 

A.  See  first  if  there  is  a  half  a  glass  of  water  in  each  boiler, 
that  the  fires  are  clean,  that  the  ashes  have  been  blown  out, 
that  some  coal  is  out  on  the  plates,  that  no  bearings  are  run- 
ning warm,  that  the  feed  pump  is  working  well,  and  that  a 
good  vacuum  is  being  carried. 

Q.  What  height  must  a  safety  valve  be  raised  or  lifted  to 
allow  a  free  escape  of  steam  equal  to  the  area  of  the  valve? 

A.  One-fourth  the  diameter;  thus  with  a  4-inch  safety 
valve  it  should  be  lifted  i  inch. 

Q.  Why  are  counterbores  put  into  each  end  of  a  cylinder? 

A.  To  allow  the  piston  to  run  over  the  edge  at  each  end  of 
the  stroke,  so  that  it  will  not  wear  shoulders  in  the  bore  of 
the  cylinder. 

Q.  A  cylinder  is  30  inches  diameter,  the  steam  pressure  is 
125  pounds,  and  30  bolts  hold  the  cylinder  cover  in  place. 
What  is  the  stress  on  each  bolt? 

A.  The  area  corresponding  to  30  inches  diameter  is  30  X 
30  X  .7854  =  706.86  square  inches,  706.86  X  125  =  88,357.5 
pounds  total  stress  on  the  cylinder  cover;  88,357.5  -i-  30  = 
2,945.25  pounds  stress  on  each  bolt. 

Q.  How  should  the  valves  be  connected  to  a  boiler? 

A.  They  should  always  be  bolted  to  the  shell,  never  riveted 
or  screwed. 

Q.  How  would  you  find  out  the  distance  the  piston  and 
shaft  had  worked  down? 

A.  It  is  customary  to  mark  on  the  cross-head  slipper  and 
cross-head  guides  the  position  of  the  piston  at  the  top  of  the 
stroke.  If  it  has  worked  down  from  the  original  position  the 
amount  will  be  the  difference  between  the  marks  on  the  guide 


EXAMINATION    QUESTIONS    AND   ANSWERS  217 

and  the  slipper.  A  tram  is  usually  furnished  with  every 
engine  showing  the  position  of  the  top  of  the  crankshaft, 
relative  to  the  facing  on  the  top  of  the  bed-plate  under  the 
bearing  caps.  If  the  shaft  is  worn  down,  the  distance  can  be 
ascertained  by  fitting  the  tram  in  place  on  the  bed-plate  facing 
and  measuring  the  space  between  the  tram  and  the  top  of  the 
crankshaft. 

Q.  What  are  the  principal  things  to  look  after  before  start- 
ing fires? 

A.  See  that  there  is  sufficient  water  in  the  boiler,  that  all 
valves  work  freely,  particularly  the  feed  check  valves ;  that 
the  air  cock  or  the  top  gage  cock  is  left  open,  to  allow  the 
air  to  escape,  and  that  all  man  and  hand-holes  are  set  up 
tightly. 

Q.  Before  turning  the  engine  over  what  precautions  are 
necessary  for  the  engine  and  vessel? 

A.  Inform  the  deck  officers  so  that  they  can  see  that  suf- 
ficient lines  are  out  to  hold  the  vessel  to  the  wharf,  and  that 
everything  is  clear  around  the  propellers.  In  the  engine-room 
see  that  the  turning  gear  is  disconnected ;  that  the  water  ser- 
vice is  turned  on ;  that  all  bearings  have  been  oiled ;  that  there 
is  nothing  in  the  crank-pits,  and  that  all  hands  are  clear  of  the 
engine. 

Q.  When  the  pumps  are  connected  to  the  engine  what 
would  you  look  after  before  starting? 

A.  See  that  the  air  pump  is  not  filled  with  water,  and  that 
all  valves  on  the  discharge  side  of  the  feed  pumps  or  bilge 
pumps  are  open. 

Q.  What  are  the  causes  of  feed  pumps  working  poorly? 

A.  Generally,  bad  management.  Either  the  pumps  are  not 
getting  the  water  from  the  hot  well  regularly  or  the  check 
valves  on  the  boilers  may  be  closed.  Possibly  the  valves  in 
the  water  end  of  the  pump  are  out  of  order. 

'The  foregoing  questions  which  I  have  quoted  cover  about 


2i8  MC  ANDREW'S  FLOATING  SCHOOL 

the  usual  ground  that  is  embodied  in  the  examination  given 
by  the  inspectors  for  your  first  papers.  I  do  not  mean  to 
imply  that  you  will  get  any  of  these  particular  questions  when 
you  go  up  for  your  tickets,  but  if  you  understand  the  princi- 
ples upon  which  each  of  them  is  worked  you  ought  to  be 
able  to  pass  any  examination  which  they  give  you. 

"This  will  conclude  my  course  of  lectures  to  you.  I  know 
I  have  not  covered  every  subject  in  marine  engineering,  as 
many  volumes  have  been  written  on  the  subject.  I  have  en- 
deavored to  give  you  a  good  general  idea  of  what  you  will 
have  to  know  to  be  successful.  You  must  not  let  up  in  your 
studies,  as  no  man  can  keep  up  to  date  unless  he  is  constantly 
studying.  By  that  I  do  not  mean  that  you  should  devote  all 
your  spare  time  to  books,  but  at  your  ages  you  should  give 
at  least  one  hour  a  day  of  your  time  off  watch  to  studying 
some  of  the  many  subjects  connected  with  your  business." 

"Chief,  can  you  recommend  us  some  good  books  to  get?" 
queried  Pierce. 

"Oh !  yes,  indeed  I  can ;  there  are  lots  of  good  books  which 
you  can  buy  which  will  be  very  helpful  to  you.  For  example, 
there  are  several  correspondence  schools  wherein  for  a  small 
sum  each  month  you  can  not  only  receive  their  courses  of 
instruction,  but  you  will  get  their  text  books  into  the  bargain. 
As  a  rule  these  books  are  excellently  gotten  up  and  will  be 
of  great  value  to  you. 

"For  a  good  all-around  text  book  on  marine  engineering  it 
is  doubtful  if  you  can  find  any  better  than  that  written  by 
Prof.  W.  F.  Durand.  He  was  once  a  sea-going  engineer  him- 
self before  he  settled  down  in  a  college,  so  he  knows  both 
the  practical  and  the  theoretical  sides  of  the  business.  Many 
of  the  best  books  on  marine  engineering  are  by  English 
authors,  as  the  whole  world  must  admit  that  Great  Britain 
has  produced  some  of  the  ablest  of  engineers,  particularly 
those  in  the  marine  branch.  When  you  get  further  along  in 


EXAMINATION    QUESTIONS    AND   ANSWERS  2IQ 

your  business  you  should  each  buy  yourself  a  copy  of  'Reed's 
Engineer's  Handbook.'  All  these  books  are,  of  course,  very 
useful  to  you,  but  you  can  each  write  your  own  book  on  the 
subject." 

"Gee !  we're  no  highbrows,"  blurted  out  O'Rourke. 

"You  don't  have  to  be  to  write  the  kind  of  book  I'm  going 
to  tell  you  about. 

"You  should  each  get  a  good-sized  blank  book,  made  of 
serviceable  paper  for  writing  with  ink  and  well  bound. 
Whenever  you  see  anything  of  interest  in  a  text  book  or  in 
any  of  the  engineering  papers  you  may  read,  copy  it  down  in 
this  notebook.  If  some  older  engineer  tells  you  of  a  good 
method  of  making  any  particular  kind  of  repairs,  or  gives 
you  any  information  that  you  think  will  be  valuable  in  the 
future,  make  copious  notes  of  them  in  your  book.  As  you 
grow  older  you  will  find  that  such  a  note  book  will  become 
invaluable  for  reference,  and  it  will  increase  in  value  to  you 
every  year  that  it  is  kept  up.  When  you  take  your  first  ex- 
amination write  down  all  the  questions  you  can  remember, 
and  work  them  out  in  your  notebook.  Even  if  they  are  not  of 
much  value  to  you  after  you  have  attained  your  license,  they 
may  help  some  young  fellow  who  is  coming  after  you  later  on. 

"When  these  lectures  which  I  have  given  you  are  published 
in  book  form,  I  am  going  to  ask  the  publishers  if  they  will 
print  in  the  back  of  the  book  a  lot  of  tables  and  useful  infor- 
mation which  every  marine  engineer  should  have  handy. 
These  will  include  tables  of  areas  of  circles,  strengths  of 
materials,  temperature  of  steam  at  different  pressures,  weights 
of  different  kinds  of  substances  with  which  marine  engineers 
have  to  deal,  etc.  I  will  also  ask  them  to  bind  with  the  book 
a  few  blank  pages,  upon  which  you  can  write  down  any  other 
bits  of  information  you  may  run  across  which  will  be  of  value 
to  you  in  your  business. 

"This  will  be  my  last  regular  talk  with  you  boys  as  a  class 


220  MC  ANDREW'S  FLOATING  SCHOOL 

in  the  'Floating  School/  but  I  will  be  only  too  glad  to  help 
you  with  any  of  your  problems  whenever  I  have  the  oppor- 
tunity. As  it  is  about  time  for  you  to  go  on  watch  you  had 
better  turn  to.  I'll  keep  my  eye  on  each  one  of  you  and  see 
that  you  get  a  chance  as  soon  as  you  can  get  your  tickets." 

"Chief,"  said  Jim  Pierce,  who  had  been  appointed  spokes- 
man of  the  class,  "I  cannot  tell  you  how  much  all  of  us 
appreciate  your  kindness  to  us.  Every  one  of  us  has  bene- 
fited a  great  deal  by  the  instruction  you  have  given  us,  and 
we  hope  to  show  you  by  what  we  accomplish  that  your  labors 
with  us  have  not  been  lost.  We  want  to  ask  you  one  parting 
favor  before  the  'Floating  School'  is  broken  up,  and  that  is  if 
you  will  do  us  the  honor  of  going  to  dinner  with  your  class 
when  we  reach  New  York." 

"That's  easy,"  laughingly  replied  McAndrew,  "of  course  I 
will." 

About  ten  days  afterward  the  Tuscarora  arrived  in  New 
York.  The  boys  had  talked  over  the  dinner  they  were  to 
have  on  every  occasion  when  they  came  together. 

O'Rourke  insisted  that  it  must  be  a  "swell  dinner,"  and  that 
"no  ordinary  West  Street  restaurant  chuck"  would  go.  To 
this  all  very  readily  agreed,  and  it  was  decided  that  they  would 
"blow  themselves  in  a  bang-up  Broadway  joint,"  as  O'Rourke 
expressed  it. 

Promptly  at  the  appointed  hour  the  four  sea  toilers,  arrayed 
in  their  best  for  the  occasion,  and  accompanied  by  Chief 
McAndrew,  sat  down  at  a  fashionable  Broadway  restaurant 
not  far  from  Forty-second  street.  They  were  not,  of  course, 
togged  out  in  evening  clothes,  as  were  most  of  the  other  men 
diners,  but  their  clean-shaven  faces,  stalwart  forms  and  gen- 
erally spick  appearance  made  them  a  very  presentable  group. 
O'Rourke  had  elected  himself  as  master  of  ceremonies,  but 
he  was  somewhat  taken  aback  when  the  polite  head  waiter 
handed  him  several  bills  of  fare,  and  asked  if  the  party  would 


EXAMINATION    QUESTIONS    AND    ANSWERS  221 

be  served  a  la  carte  or  table  d'hote.  After  getting  his  breath 
he  replied : 

"Aw,  cut  out  that  frog-eater's  chatter  and  give  us  the  best 
chow  you've  got  in  the  joint." 

McAndrew  came  to  the  waiter's  rescue,  and  told  him  to 
serve  the  dinners  table  d'hote,  afterwards  explaining  to  his 
hosts  that  that  meant  they  would  have  to  pay  only  $1.50  each 
for  the  dinner,  and  that  they  would  get  a  very  good  meal  for 
less  than  it  would  cost  them  on  the  other  plan. 

What  the  boys  lacked  in  style  they  made  up  in  robust  appe- 
tites, so  as  each  course  was  served  it  was  quickly  disposed 
of  with  a  noticeable  lack  of  the  usual  picking  and  faultfinding 
indulged  in  by  the  habitues  of  such  places.  True,  there  was 
somewhat  of  a  mix-up  In  the  use  of  a  multiplicity  of  knives, 
forks  and  spoons  placed  at  each  plate,  but  each  was  made  to 
serve  a  good  purpose,  even  if  Schmidt  did  try  to  eat  his  fish 
course  with  a  combined  fork  and  spoon  usually  reserved  for 
the  ice  cream. 

The  menu  was  printed  in  French,  which  caused  much  specu- 
lation as  to  the  composition  of  the  next  course,  and  some 
grave  doubts  as  to  the  course  under  consideration  at  the  time. 

O'Rourke  had  looked  forward  with  great  expectation  to  the 
viand  described  as  "pommes  de  terre  au  naturel,"  and  could 
not  refrain  from  venting  his  disappointment  when  they  were 
served,  by  shouting  out,  "Gee !  they're  nothing  but  plain  old 
boiled  spuds  with  some  grass  on  them." 

When  the  "cafe  demi-tasse"  was  served  at  the  conclusion  of 
the  meal,  he  nearly  precipitated  a  small  riot  by  demanding  in 
loud  tones  that  he  be  given  "a  man's  size  cup  of  coffee." 

However,  the  influence  of  the  good  dinner  soon  calmed  his 
ruffled  temper,  and  when  the  real  Havanas,  not  Savannahs,  as 
O'Rourke  announced  he  had  been  accustomed  to  smoking, 
were  lighted,  all  was  serene  at  the  table. 

Drawing  a  small  package  from  his  pocket,  Pierce,  in  a  few 


222  MC  ANDREWS   FLOATING    SCHOOL 

well-chosen  and  heartfelt  words,  presented  it  to  McAndrew. 
Upon  opening  the  package,  McAndrew  found,  to  his  complete 
surprise,  that  it  contained  a  handsome  gold  watch  and  chain. 
Upon  the  back  of  the  watch  was  neatly  engraved  the  fol- 
lowing : 

"To  Chief  Engineer  James  Donald  McAndrew,  with  the 
highest  esteem  and  gratitude  of  his  pupils  in  the  'Floating 
School.' " 

Quite  overcome  with  this  evidence  of  his  pupils'  apprecia- 
tion of  his  efforts,  McAndrew  cleared  his  throat  and  said : 

"Boys,  what  I  have  done  for  you  was  not  with  the  hope  of 
getting  any  such  handsome  reward  as  this,  but  from  the 
interest  which  I  take  in  young  men  who  are  anxious  to  ad- 
vance themselves  in  their  life  work.  Each  one  of  you  has  the 
making  of  a  good  engineer  in  you,  and  I  wish  for  you  all 
every  success  in  your  efforts  to  advance.  If  my  instructions 
serve  to  help  you  in  accomplishing  the  first  steps  in  your  ad- 
vancement I  shall  feel  more  than  repaid.  When  you  get 
further  along,  and  want  to  try  for  higher  grades  of  licenses, 
I  shall,  if  you  desire,  and  if  conditions  are  such  that  we  can 
all  be  together  again,  be  only  too  glad  to  try  to  aid  you  in  the 
same  manner  that  I  have  attempted  to  do  with  the  'Floating 
School.' " 

"We'll  have  to  call  it  the  'Floating  High  School/"  re- 
sponded O'Rourke,  who  was  bound  to  have  the  last  word. 

THE  END 


Useful  Tables  for  Marine 
Engineers 


224 


MC  ANDREW'S  FLOATING  SCHOOL 


Properties  of  Saturated  Steam. 

(Condensed  from  Marks  and  Davis's  Steam  Tables  and  Diagrams,  1909, 
by  permission  of  the  publishers,  Longmans,  Green  &  Co.) 


m 

•f  • 

Total  Heat 

5i 

3* 

. 

0> 

a 

•§£ 

B"! 

above  32°  F  . 

j 

£° 

OH] 

3 

| 

C  3 
*"^  o 

£cc 

§'S 

v      o3 

S 

gW 

s  -a 

II 

•8 

5 

|a 

%  a 
« 

II 

1-1 

1*1 

,     o5 

gto.-2 
*     a 

oT_  S 

*! 

l! 

n 

li 

11 

c3  ° 

JH 

Bfe 

•2    1 

•3      g 

•f.SaQ 

i_ 

"£» 

a° 

*" 

H 

a    W 

hH        W 

H 

> 

*~ 

H 

W 

29.74 

0.0886 

32 

0.00 

1073.4 

1073.4 

3294 

0.000304 

0.0000 

.1832 

29.67 

0.1217 

40 

8.05 

1076.9 

1068.9 

2438 

0.000410 

0.0162 

.1394 

29.56 

0.1780 

50 

18.08 

1081.4 

1063.3 

1702 

0.000587 

0.0361 

.0865 

29.40 

0.2552 

60 

28.08 

1085.9 

1057.8 

1208 

0.000828 

0.0555 

.0358 

29.18 

0.3626 

70 

38.06 

1090.3 

1052.3 

871 

0.001148 

0.0745 

.9868 

28.09 

0.505 

80 

48.03 

1094.8 

1046.7 

636.8 

0.001570 

0.0932 

.9398 

28.50 

0.696 

90 

58.00 

1099.2 

1041.2 

469.3 

0.002131 

0.1114 

.8944 

28.00 

0.946 

100 

67.97 

1103.6 

1035.6 

350.8 

0.002851 

0.1295 

.8505 

27.83 

1 

101.83 

69.8 

1104.4 

1034.6 

333.0 

0.00300 

0.1327 

.8427 

25.85 

2 

126.15 

94.0 

1115.0 

1021.0 

173.5 

0.00576 

0.1749 

.7431 

23.81 

3 

141.52 

109.4 

1121.6 

1012.3 

118.5 

0.00845 

0.2008 

.6840 

21.78 

4 

153.01 

120.9 

1126.5 

1005.7 

90.5 

0.01107 

0.2198 

.6416 

19.74 

5 

162.28 

130.1 

1130.5 

1030.3 

73.33 

0.01364 

0.2348 

.6084 

17.70 

6 

170.06 

137.9 

1133.7 

995.8 

61.89 

0  01616 

0.2471 

.5814 

15.67 

7 

176.85 

144.7 

1136.5 

991.8 

53.56 

0.01867 

0.2579 

.5582 

13.63 

8 

182.86 

150.8 

1139.0 

938.2 

47.27 

0.02115 

0.2673 

.5380 

11.60 

9 

188.27 

156.2 

1141.1 

985.0 

42.36 

0.02361 

0.2756 

.5202 

9.56 

10 

193.22 

161.1 

1143.1 

982.0 

38.38 

0.02606 

0.2832 

.5042 

7.52 

11 

197.75 

165.7 

1144.9 

979.2 

35.10 

0.02849 

0.2902 

.4895 

5.49 

12 

201  .96 

169.9 

1146.5 

976.6 

32.36 

0.03090 

0.2967 

.4760 

3.45 

13 

205.87 

173.8 

1148.0 

974.2 

30.03 

0.03330 

0.3025 

.4639 

1.42 

14 

209.55 

177.5 

1149.4 

971.9 

28.02 

0.03569 

0.3081 

.4523 

Ibs. 

gage. 

14.70 

212 

180.0 

1150.4 

970.4 

26.79 

0.03732 

0.3118 

.4447 

03 

15 

213.0 

181.0 

1150.7 

969.7 

26.27 

0.03806 

0.3133 

.4416 

1.3 

16 

216.3 

184.4 

1152.0 

967.6 

24.79 

0.04042 

0.3183 

.4311 

2.3 

17 

219.4 

187.5 

1153.1 

965.6 

23.38 

0.04277 

0.3229 

.4215 

3.3 

18 

222.4 

190.5 

1154.2 

963.7 

22.16 

0.04512 

0.3273 

.4127 

4.3 

19 

225.2 

193.4 

1155.2 

961.8 

21.07 

0.04746 

0.3315 

.4045 

5.3 

20        • 

228.0 

196.1 

1156.2 

960.0 

20.08 

0.049«) 

0.3355 

.3965 

6.3 

21 

230.6 

198.8 

1157.1 

958.3 

19.18 

0.05213 

0.3393 

.3887 

7.3 

22 

233.1 

201.3 

1158.0 

956.7 

18.37 

0.05445 

0.3430 

.3811 

8.3 

23 

235.5 

203.8 

1158.8 

955.1 

17.62 

0.05676 

0.3465 

.3739 

9.3 

24 

237.8 

205.1 

1159.6 

953.5 

16.93 

0.05907 

0.3499 

.3670 

10.3 

25 

240.1 

208.4 

1160.4 

952.0 

16.30 

0.0614 

0.3532 

1.3604 

11.3 

25 

242.2 

210  6 

1161.2 

950..  6 

15.72 

0.0636 

0.3564 

1  .3542 

12.3 

27 

244.4 

212.7 

1161.9 

949.2 

15.18 

0.0659 

0.3594 

1.3483 

13.3 

23 

246.4 

214.8 

1162.6 

947.8 

14.67 

0.0682 

0.3623 

1.3425 

14.3 

29 

248.4 

216.8 

1163.2 

946.4 

14.19 

0.0705 

0.3652 

1  .3367 

15.3 

30 

250.3 

218.8 

1163.9 

945.1 

13.74 

0.0728 

0.3680 

1.3311 

15.3 

31 

252.2 

220.7 

1164.5 

943.8 

13.32 

0.0751 

0.3707 

1.3257 

17.3 

32 

254.1 

222.6 

1165.1 

942.5 

12.93 

0.0773 

0.3733 

1.3205 

18.3 

33 

255.8 

224.4 

1165.7 

941.3 

12.57 

0.0795 

0.3759 

.3155 

19.3 

34 

257.6 

225.2 

1166.3 

940.1 

12.22 

0.0818 

0.3784 

.3107 

20.3 

35 

259.3 

|27.9 

1166.8 

938.9 

11.89 

0.0841 

0.3808 

.3060 

21.3 

36 

261,0 

1167.3 

937.7 

11.58 

0.0863 

0.3832 

.3014 

22.3 

37 

262.6 

231  '.3 

1167.8 

936.6 

11.29 

).0886 

0.3855 

.2969 

23.3 

38 

264.2 

232.9 

1168.4 

935.5 

11.01 

0.0908 

0  <877 

.2925 

24.3 

39 

265.8 

234.5 

1168.9 

934.4 

10.74 

0.0931 

03899 

.2882 

25.3 

40 

267.3 

236.1 

1169.4 

933.3 

10.49 

0.0953 

0.3920 

.28^1 

25.3 

41 

268.7 

237.6 

1169.8 

932.2 

10.25 

0.0976 

0.3941 

.2800 

Republished   by   permission   of   Messrs.   John   Wiley  &  Sons,    Inc. 
from    Kent's   Mechanical   Engineers   Pocket- Book. 


USEFUL  TABLES  FOR  MARINE  ENGINEERS 
Properties  of  Saturated  Steam.    (Continued.) 


225 


fa 

£  e 

Total  Heat 

^ 

~ 

T 

3T- 

I  c- 

.  . 

above  32°  F. 

«fl 

£"3 

—  -- 

6*3 

•3 

5 

IOQ 

1" 

|| 

«      « 

1    -2 

IS 

6-° 

«-§" 

"8 

Sc 

K 

o>  a 

ng 

p 

"3     'c 

2*3 

•5    S 

1*3 

I   ^ 

tl 

i 

£fc 

S3 

il 

3 

1 

H^ 

2    M 

c    K 

J 

i>~ 

^ 

W 

i 

27.3 

42 

270.2 

239.1 

1170.3 

931.2 

10.02 

0.0998 

0  3962 

2759 

23.3 

43 

271.7 

240.5 

1170.7 

933.2 

9.80 

0.1020 

0.3982 

2720 

29  3 

44 

273.1 

242.0 

1171.2 

929.2 

9.59 

0.1043 

0.4002 

2681 

33.3 

45 

274.5 

243.4 

1171.6 

923.2 

9.39 

0.1065 

0  4021 

.2644 

31.3 

46 

275.8 

244.8 

1172.0 

927.2 

9.20 

0.1087 

0.4040 

2607 

32.3 

47 

277.2 

246.1 

1172.4 

926.3 

9.02 

0.1109 

0.4059 

2571 

33.3 

43 

278  5 

247.5 

1172  8 

925.3 

8.84 

0.1131 

0  ^V)77 

2336 

34.3 

49 

279.8 

243.8 

1173.2 

924.4 

8  67 

0.1153 

0^4095 

'2502 

33.3 

50 

281.0 

250.1 

1173.6 

923.5 

8.51 

0.1175 

0.4113 

2468 

35.3 

51 

282.3 

251.4 

1174.0 

922.6 

8.35 

0.1197 

0  4130 

2432 

37.3 

52 

283.5 

252.6 

1174.3 

921.7 

8.20 

0.1219 

0.4147 

'2405 

33.3 

53 

284  7 

253.9 

1174.7 

920.8 

8.05 

0.1241 

0.4164 

2370 

39.3 

54 

285.9 

255.1 

1175.0 

919.9 

7.91 

0.1263 

0.4180 

.2339 

40.3 

55 

237.1 

255.3 

1175.4 

919.0 

7.73 

0.1285 

0.4196 

2309 

41.3 

56 

238.2 

257.5 

1175.7 

918.2 

7.65 

0.1307 

0.4212 

2278 

42.3 

57 

239.4 

258.7 

1176.0 

917.4 

7.52 

0.1329 

0.4227 

.2248 

43.3 

58 

290.5 

259.8 

1176.4 

916.5 

7.40 

0  1350 

0.4242 

.2218 

44.3 

59 

291.6 

261.0 

1176.7 

915.7 

7.23 

0.1372 

0.4257 

2189 

45.3 

60 

292.7 

262.1 

1177.0 

914.9 

7.17 

0.1394 

0.4272 

.2160 

45.3 

61 

293.8 

263.2 

1177.3 

914.1 

7.05 

0.1416 

0.4287 

.2132 

47.3 

62 

294.9 

254.3 

1177.6 

913.3 

6.93 

0.1438 

0.4302 

2104 

43.3 

63 

295.9 

265.4 

1177.9 

912.5 

6.85 

0.1450 

0.4316 

.2077 

49.3 

64 

297.0 

256.4 

1178.2 

911.8 

6.75 

0.1482 

0.4330 

.2050 

50.3 

65 

293.0 

257.5 

1178.5 

911.0 

6.65 

0.1503 

0.4344 

2024 

51.3 

66 

299.0 

253.5 

1178.8 

910.2 

6.56 

0.1525 

0.4358 

1998 

52.3         67 

303.0 

259.6 

1179.0 

909.5 

6.47 

0.1547 

0.4371 

.1972 

53.3 

68 

301.0 

270.6 

1179.3 

933.7 

6.38 

0.1569 

0.4385 

.1946 

54.3 

69 

302.0 

271.6 

1179.6 

933.0 

6.29 

0.1590 

0.4398 

1921 

55.3 

70 

302.9 

272.6 

1179.8 

937.2 

6  20 

0.1612 

0.4411 

.1896 

56.3 

71 

303.9 

273.6 

1180.1 

935.5 

6.12 

0.1634 

0.4424 

.1872 

57.3 

72 

304.8 

274.5 

1133.4 

903.8 

6.04 

0.1656 

0.4437 

.1848 

58.3 

73 

305.8 

275.5 

1130.  6 

905.1 

5.95 

0.1678 

0.4449 

.1825 

59.3 

74 

306.7 

276.5 

1133.9 

904.4 

5.89 

0.1699 

0.4462 

.1801 

60.3 

75 

307.6 

277.4 

1181.1 

903.7 

5.81 

0.1721 

0.4474 

.1778 

61.3 

76 

303.5 

273.3 

1181.4 

903.0 

5.74 

0.1743 

0.4487 

.1755 

62.3 

77 

309.4 

279.3 

1181.  6 

902.3 

5.67 

0.1764 

0.4499 

.1730 

63.3 

73 

310.3 

280.2 

1181.8 

901.7 

5.60 

0.1785 

0.4511 

.1712 

64.3 

79 

311.2 

231.1 

1182.1 

901.0 

5.54 

0.1803 

0.4523 

.1687 

65.3 

80 

312.0 

232.0 

1182.3 

933.3 

5.47 

0.1829 

0.4535 

.1665 

66.3 

81 

312.9 

232.9 

1182.5 

899.7 

5.41 

0.1851 

0.4546 

.1644 

67.3 

82 

313.8 

233.8 

1182.8 

899.0 

5.34 

0.1873 

0.4557 

.1623 

68.3 

83 

314.6 

284.6 

1133.0 

893.4 

5.28 

0.1894 

0.4568 

.1602 

69.3 

84 

315.4 

283.5 

1183.2 

897.7 

5.22 

0.1915 

0.4579 

.1581 

70.3 

85 

316.3 

285.3 

1183.4 

897.1 

5.16 

0.1937 

0.4590 

1561 

71.3 

86 

317.1 

237.2 

1183.6 

895.4 

5.10 

0  1959 

0.4601 

1540 

72.3 

87 

317.9 

283.0 

1183.8 

895.8 

5.05 

0.1980 

0.4612 

1520 

73.3 

88 

318.7 

283.9 

1  184.0 

895.2 

5  00 

0.2001 

0.4623 

.1500 

74.3 

89 

319.5 

239.7 

1184.2 

894.6 

4.94 

0.2023 

0.4633 

1481 

75.3 

90 

320.3 

290.5 

1184.4 

893.9 

4.89 

0.2044 

0.4644 

1461 

76.3 

91 

321.1 

291.3 

1184.6 

893.3 

4.84 

0.2065 

0.4654 

1442 

77.3 

92 

321.8 

292  1 

1184.8 

892.7 

4.79 

0.2087 

0.4664 

1423 

73.3 

93 

322.6 

292.9 

1185.0 

892.1 

4.74 

0.2109 

0.4674 

1404 

79.3 

94 

323.4 

293.7 

1185  2 

891.5 

4.69 

0.2130 

0  4584 

1385 

80.3 

95 

324.1 

294.5 

1185.4 

890.9 

4.65 

0.2151 

0.4694 

1367 

226 


MC  ANDREW'S  FLOATING  SCHOOL 


Properties  of  Saturated  Steam.    (Continued.) 


£"-• 

g  a 

Total  Heat 

^^ 

^ 

cu 

ft 

M 

13 

3^ 

above  32°  F. 

^"S 

fa*o 

Oh-! 

•— 

03 

UU1 

P 

II 

|w 

P.a 

~  g" 

* 

H 

<"          a 

6     u 

£  o 

PH  £ 

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t.  53 
a  £ 

^        P 

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H 

£        E 

£           * 

jp§ 

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11 

W 

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W 

81.3 

96 

324.9 

295.3 

1185.6 

890.3 

4.60 

0.2172 

0.4704 

1348 

82.3 

97 

325.6 

296.1 

1185.8 

889.7 

4.56 

0.2193 

0.4714 

.1330 

83.3 

93 

326.4 

296.8 

1185.0 

689.2 

4.51 

0.2215 

0.4724 

.1312 

G4.3 

99 

327.1 

297.6 

1185.2 

888.6 

4.47 

0.2237 

0.4733 

.1295 

85.3 

100 

327.8 

293.3 

1!36.3 

888.0 

4.429 

0.2253 

0  4743 

.1277 

87.3 

102 

329.3 

299.8 

1186.7 

886.9 

4.347 

0.2300 

0.4762 

.1242 

89.3 

104 

330.7 

301.3 

1187.0 

885.8 

4.268 

0.2343 

0.4780 

.1208 

91.3 

106 

332.0 

302.7 

1187.4 

884.7 

4.192 

0.2335 

0  4798 

.1174 

93.3 

103 

333.1 

304.1 

1187.7 

883.6 

4.118 

0.2429 

0.4816 

.1141 

95.3 

110 

334.8 

305.5 

1188.0 

882.5 

4.047 

0  2472 

0.4834 

.1108 

97.3 

112 

335.1 

305.9 

1  188.  4 

881.4 

3.978 

0.2514 

0.4852 

.1076 

99.3 

114 

337.4 

303.3 

1188.7 

880.4 

3.912 

0.2556 

0.4869 

1045 

UI.3 

116 

338.7 

309.6 

1189.0 

879.3 

3.848 

0.2599 

0  4885 

.1014 

103.3 

118 

340.0 

311.0 

1189.3 

878.3 

3.786 

0.2641 

0.4903 

.0984 

105.3 

120 

341.3 

312.3 

1189.6 

877.2 

3.726 

0  2683 

0.4919 

0954 

107.3 

122 

342.5 

313.6 

1189.8 

876.2 

3.668 

0.2726 

0.4935 

.0924 

109.3 

124 

343.8 

314.9 

1190.1 

875.2 

3.611 

0.2769 

0.4951 

.0895 

111.3 

125 

345.0 

316.2 

1190.4 

874.2 

3.556 

0.2812 

0.4967 

.0865 

113.3 

123 

346.2 

317.4 

1190.7 

873.3 

3  504 

0.2854 

0.49.2 

.0837 

115.3 

130 

347.4 

318.6 

1191.0 

872.3 

3.452 

0.2897 

0.4998 

.0809 

117.3 

132 

348.5 

319.9 

1191.2 

871.3 

3.402 

0.2939 

0.5013 

.0782 

119.3 

134 

349.7 

321.  1 

1191.5 

870.4 

3.354 

0.2981 

0.5028 

.0755 

121.3 

136 

350.8 

322.3 

1191.7 

869.4 

3.308 

0  3023 

0.5043 

.0728 

123.3 

138 

352.0 

323.4 

1192.0 

868.5 

3.263 

0.3065 

0  5057 

.0702 

125.3 

149 

353.1 

324.6 

1192.2 

867.6 

3.219 

0.3107 

0.5072 

.0675 

127.3 

142 

354.2 

325.8 

1192.5 

866.7 

3.175 

0.3150 

0.5086 

.0649 

129.3 

144 

355.3 

326.9 

1192.7 

865.8 

3.133 

0.3192 

0.5100 

.0624 

131  3 

145 

355.3 

328.0 

1192.9 

864.9 

3.092 

0.3234 

0.5114 

.0599 

133.3 

143 

357.4 

329.1 

1193.2 

864.0 

3.052 

0  3276 

0.5128 

.0574 

135.3 

150 

358.5 

330.2 

1193.4 

863.2 

3  012 

0.3320 

0.5142 

.0550 

137.3 

152 

359.5 

331.4 

1193.6 

862.3 

2.974 

0.3362 

0.5155 

.0525 

139.3 

154 

350.5 

332.4 

1193.8 

861.4 

2.938 

0  3404 

0.5169 

.0501 

141.3 

156 

3o1.6 

333.5 

1194.1 

860.6 

2.902 

0.3446 

0.5182 

.0477 

143.3 

158 

352.6 

334.6 

1194.3 

859.7 

2.868 

0  3488 

0.5195 

.0454 

145.3 

160 

363.6 

335.6 

1194.5 

858.8 

2.834 

0.3529 

0.5208 

.0431 

147.3 

162 

364.6 

336.7 

1194.7 

858.0 

2.801 

0.3570 

0.5220 

.0409 

149.3 

164 

365.6 

337.7 

1194.9 

857.2 

2.769 

0.3612 

0.5233 

.0387 

151.3 

166 

365.5 

338.7 

1195.1 

856.4 

2.737 

0.3654 

0  5245 

.0365 

153.3 

168 

357.5 

339.7 

1195.3 

855.5 

2.706 

0  3696 

0.5257 

.0343 

155.3 

170 

358.5 

340.7 

1195.4 

854.7 

2.675 

0.3738 

0.5269 

0321 

157.3 

172 

359.4 

341.7 

1195.6 

853.9 

2.645 

0  3780 

0.5281 

.0300 

159.3 

174 

370.4 

342.7 

1195.8 

853.1 

2.616 

0.3822 

0.5293 

0278 

161.3 

175 

371.3 

343.7 

11%.  0 

852.3 

2.588 

0.3864 

0  5305 

0257 

153.3 

173 

372.2 

344.7 

1196.2 

851.5 

2  560 

0  3906 

0.5317 

.0235 

165  3 

180 

373.1 

345.6 

1196.4 

850.8 

2.533 

0.3948 

0.5328 

.0215 

167.3 

182 

374.0 

346.6 

1195.6 

850.0 

2.507 

0.3989 

0.5339 

.0195 

159.3 

184 

374.9 

347.6 

1195.8 

849.2 

2.481 

0.4031 

0.5351 

.0174 

171.3 

186 

375.8 

348.5 

1196.9 

848.4 

2.455 

0.4073 

0.5362 

0154 

173.3 

183 

376.7 

349.4 

1197.1 

847.7 

2.430 

0.4115 

0.5373 

.0134 

175  3 

190 

377.6 

350.4 

1197.3 

846.9 

2.406 

0.4157 

0  5384 

.0114 

177.3 

192 

378.5 

351.3 

1197.4 

846.1 

2.381 

0.4199 

0.5395 

.0095 

179.3 

194 

379.3 

352.2 

1197.6 

845.4 

2.358 

0.4241 

0.5405 

.0076 

181  3 

196 

380.2 

353.1 

1197.8 

844.7 

2.335 

0.4283 

0.5416 

.0056 

183.3 

198 

381.0 

354.0 

1197.9 

843.9 

2.312 

0.4325 

0.5426 

.0038 

USEFUL  TABLES  FOR  MARINE  ENGINEERS 

Properties  of  Saturated  Steam.    (Continued.) 


227 


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190.3 

205 

384.0 

357.1 

1198.5 

841.4 

2.237 

0.447 

0.5463 

0.9973 

195  3 

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386.0 

359.2 

1198.8 

839.6 

2.187 

0.457 

0  5488 

0  9928 

200.3 

215 

388.0 

361.4 

1  199.  2 

837.9 

2.138 

0.468 

0.5513 

0.9885 

205.3 

220 

389.9 

363.4 

1199.6 

836.2 

2  091 

0.478 

0.5538 

0.9841 

210.3 

225 

391.9 

365.5 

1199.9 

834.4 

2.046 

0.489 

0.5562 

0  9799 

215.3- 

230 

393.8 

367.5 

1200.2 

832.8 

2.004 

0.499 

0  5586 

0.9758 

220.3 

235 

395.6 

369.4 

1200.6 

831.1 

I  964 

0.509 

0.5610 

0.9717 

225.3 

240 

397.4 

371.4 

1200.9 

829.5 

1.924 

0.520 

0.5633 

0.9676 

230.3 

245 

399.3 

373.3 

1201.2 

827.9 

1.887 

0.530 

0.5655 

0  9638 

235.3 

250 

401.1 

375.2 

1201.5 

825.3 

1.850 

0.541 

0.5676 

0.9600 

245.3 

260 

404.5 

378.9 

1202.1 

823.1 

1  782 

0.561 

0  5719 

0.9525 

255.3 

270 

407.9 

382.5 

1202.6 

820.1 

1.718 

0  582 

0.5760 

0  9454 

255.3 

280 

411.  2 

385.0 

1203.1 

817.1 

1  658 

0.603 

0.5800 

0.9385 

275.3 

290 

414.4 

389.4 

1203.6 

814.2 

1.602 

0.624 

0.5840 

0  9316 

285.3 

300 

417.5 

392.7 

1204.1 

811.3 

1.551 

0.645 

0.5878 

0.9251 

295.3 

310 

420.5 

395.9 

1204.5 

808.5 

1.502 

0.666 

0  5915 

0  9187 

305.3 

320 

423.4 

399.1 

1204.9 

805.8 

1.456 

0  687 

0.5951 

0.9125 

315.3 

330 

425.3 

402.2 

1205.3 

803.1 

1.413 

0.708 

0  5986 

0.9065 

325.3 

340 

429.1 

405.3 

1205.7 

800.4 

1.372 

0  729 

0.6020 

0  9005 

335.3 

350 

431.9 

408.2 

1205.1 

797.8 

1  334 

0.750 

0.6053 

0.8949 

345.3 

360 

434.6 

411.2 

1205.4 

795.3 

1.298 

0.770 

0.6085 

0  8894 

355.3 

370 

437.2 

414.0 

1205.8 

792.8 

1.264 

0.791 

0.6116 

0.8840 

355.3 

380 

439.8 

416.8 

1207.1 

790.3 

1.231 

0.812 

0  6147 

0.8788 

375.3 

390 

442.3 

419.5 

1207.4 

787.9 

1.200 

0.833 

0.6178 

0.8737 

385.3 

400 

444.8 

422 

1203 

786 

1.17 

0.86 

0.621 

0.868 

435.3 

450 

456.5 

435 

1209 

774 

1.04 

0.96 

0.635 

0.844 

485.3 

500 

467.3 

448 

1210 

762 

0.93 

1.08 

0.648 

0.822 

535.3 

550 

477.3 

459 

1210 

751 

0.83 

1.20 

0.659 

0.801 

585.3 

600 

485.6 

459 

1210 

741 

0.76 

1.32 

0.670 

0.783 

Available  Energy  in  Expanding  Steam.  —  Rankine  Cycle.  (J.  B. 
Stan  wood,  Power,  June  9,  1908.)  —  A  simple  formula  for  finding,  with  tha 
aid  of  the  steam  and  entropy  tables,  the  available  energy  per  pound  of 
steam  in  B.T.U.  when  it  is  expanded  adiabatically  from  a  higher  to  a 
lower  pressure  is: 

U  =  H  -  Hi  +  T  (Ni  -  N). 

U  =  available  B.T.U.  in  1  Ib.  of  expanding  steam;  H  and  H\  total  heat 
in  1  Ib.  steam  at  the  two  pressures;  T  =  absolute  temperature  at  the 
lower  pressure;  N  —  N\,  difference  of  entropy  of  1  Ib.  of  steam  at  the  two 
pressures. 

EXAMPLE.  —  Required  the  available  B.T.U.  in  1  Ib.  steam  expanded 
from  100  Ibs.  to  14.7  Ibs.  absolute.  H  =  1186.3;  Hi  =  1150.4;  T  =  672; 
N  =  1.602;  Ni  =  1.756.  35.9  +  103.5  =  138.4. 

Efficiency  of  the  Cycle.  —  Let  the  steam  be  made  from  feed-water  at 
212°.  Heat  required  =  1186.3  -  180  =  1006.3;  efficiency  =  138.4  -*- 
1006.3  =  0.1375. 

Rankine  Cycle.  —  This  efficiency  is  that  of  the  Rankine  cycle,  which 
assumes  that  the  steam  is  expanded  adiabatically  to  the  lowest  pressure 
and  temperature,  and  that  the  feed-water  from  which  the  steam  is  made 
is  introduced  into  the  system  at  the  same  low  temperature. 

Carnot  Cycle.  —  The  Carnot  ideal  cycle,  which  assumes  that  all.  the 
heat  entering  the  system  enters  at  the  highest  temperature,  and  in  which 
the  efficiency  is  (Ti  -  Tt)  +  Ti,  gives  (327.8-  212)  -*-  (327.8+  460)  = 
0  1470  and  the  available  energy  inB.T.U.=0. 1470X1006.3  =  147.9  B.T.U. 


228  MC  ANDREW'S  FLOATING  SCHOOL 

WIRE  AND  SHEET-METAL,  GAUGES  COMPARED. 


Sc  • 

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-0   6 

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British  Imperial 

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0000000 

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7.62 

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.284 

.25763 

.263 

.219 

.276 

7.01 

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2 

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.259 

.22942 

.244 

.212 

.252 

6.4 

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3 

4 

.23-3 

.20431 

.225 

.207 

.232 

5.89 

.234 

4 

5 

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.18194 

.207 

.204 

.212 

5.38 

.219 

5 

6 

.203 

.16202 

.192 

.201 

.192 

4.88 

.203 

6 

7 

.18 

.14428 

.177 

.199 

.176 

4.47 

.188 

7 

8 

.165 

.12849 

.162 

.197 

.16 

4.06 

.172 

8 

9 

.148 

.11443 

.148 

.194 

.144 

3.66 

.156 

9 

10 

.134 

.J0189 

.135 

.191 

.128 

3.25 

.141 

10 

11 

.12 

.09074 

.12 

.188 

.116 

2.95 

.125 

11 

12 

.109 

.08081 

.105 

.185 

.104 

2.64 

.109 

12 

13 

.095 

.07196 

.092 

.182 

.092 

2.34 

.094 

13 

14 

.033 

.06408 

.08 

.180 

.08 

2.03 

.078 

14 

15 

.072 

.05707 

.072 

.178 

.072 

1.83 

.07 

15 

16 

.065 

.05032 

.063 

.175 

.064 

1.63 

.0625 

16 

17 

.053 

.04526 

.054 

.172 

.056 

1.42 

.0563 

17 

18 

.049 

.0403 

.047 

.168 

.048 

1.22 

.05 

18 

19 

.042 

.03589 

.041 

164 

.04 

1.02 

.0438 

19 

20 

.035 

.03196 

.035 

.161 

.036 

.91 

.0375 

20 

21 

.032 

.02846 

.032 

.157 

.032 

.81 

.0344 

21 

22 

028 

.02535 

.028 

.155 

.028 

.71 

.0313 

22 

23 

.025 

.02257 

.025 

.153 

.024 

.61 

.0281 

23 

24 

.022 

.0201 

.023 

.151 

.022 

.56 

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24 

25 

.02 

.0179 

.02 

.148 

.02 

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.0219 

25 

26 

.018 

.01594 

.018 

.146 

.018 

.46 

.0188 

26 

27 

.016 

.01419 

.017 

.143 

.0164 

.42 

.0172 

27 

28 

.014 

.01264 

.016 

.139 

.0148 

.38 

.0156 

28 

29 

.013 

.01126 

.015 

.134 

.0136 

.35 

.0141 

29 

30 

.012 

.01002 

.014 

.127 

.0124 

.31 

.0125 

30 

31 

.01 

.00893 

.013 

.120 

.0116 

.29 

.0109 

31 

32 

.009 

.00795 

.013 

.115 

.0108 

.27 

.0101 

32 

33 

.003 

.00708 

.011 

.112 

.01 

.25 

.0094 

33 

34 

.007 

.0063 

.01 

.110 

.0092 

.23 

.0086 

34 

35 

.005 

.00561 

.00 

.108 

.0084 

.21 

.0078 

35 

36 

.004 

.005 

.009 

.106 

.0076 

.19 

.007 

36 

37 

.00445 

.0085 

.103 

.0068 

.17 

.0066 

37 

38 

.00396 

.008 

.101 

.006 

.15 

.0063 

38 

39 

.00353 

.0075 

099 

.0052 

.13 

39 

40 

.00314 

.007 

097 

.0048 

.12 

40 

41 

.095 

.0044 

.11 

41 

42 

.092 

.004 

.10 

42 

43 

.088 

.0036 

.09 

43 

44 

.085 

.0032 

.08 

44 

45 

.081 

.0028 

.07 

45 

46 

.079 

.0024 

.06 

46 

47 

.077 

.002 

.05 

47 

48 

.075 

.0016 

.04 

48 

49 

.092 

.0012 

.03 

49 

50 

.069 

.001 

.025 

50 

Republished    by  permission   of   Messrs.   John   Wiley  &  Sons, 
from    Kent's   Mechanical   Engineers   Pocket- Book. 


Inc. 


USEFUL  TABLES  FOR  MARINE  ENGINEERS 


229 


SQUARES,   CUBES,   SQUARE  ROOTS  AND  CUBE  ROOTS  OF 
NUMBERS  FROM  O.I  TO    16OO. 


No. 

Square 

Cube. 

Sq. 
Root. 

Cube 
Root. 

No. 

Square. 

Cube. 

Sq. 
Root. 

Cube 
Root. 

0.1 

.01 

.001 

.3162 

.4642 

3.1 

9.61 

29.791 

.761 

^ 

.15 

.0225 

.0034 

.3873 

.5313 

.2 

10.24 

32.768 

.789 

.474 

.2 

.04 

.008 

.4472 

.5846 

.3 

1089 

35.937 

.817 

489 

.25 

.0625 

.0156 

.500 

.6300 

4 

11.56 

39.304 

.844 

504 

.3 

.09 

.027 

.5477 

.6694 

.5 

12.2!) 

42.875 

.871 

.518 

.35 

.1225 

.0429 

.5916 

.7047 

.6 

12.96 

46656 

.897 

533 

.4 

16 

.064 

.6325 

.7368 

.7 

13.69 

50.653 

.924 

.547 

.45 

.2025 

.0911 

.6708 

.7663 

.8 

14.44 

54.872 

.949 

.560 

.5 

.25 

.125 

.7071 

.793} 

.9 

15.21 

59.319 

.975 

574 

.55 

.3025 

.1664 

.7416 

.8193 

4. 

16. 

64. 

2. 

.5874 

.6 

.36 

.216 

.7746 

.8434 

1 

16.81 

68.921 

2025 

.601 

.65 

.4225 

.2746 

.8062 

.8662 

.2 

17.64 

74.088 

2049 

.613 

.7 

.49 

.343 

.8367 

.88?c 

.3 

18.49 

79.507 

2.C74 

.626 

.75 

.5625 

.4219 

.8660 

.9086 

.4 

19.36 

85.184 

2.C98 

1.639 

.8 

.64 

.512 

.8944 

.9283 

.5 

20.25 

91.125 

2.121 

1.651 

.85 

.7225 

.6141 

.9219 

.9473 

.6 

21.16 

97.336 

2.145 

1  .663 

9 

.81 

.729 

.9487 

.9655 

.7 

22.09 

103.823 

2  1C8 

1  b75 

.95 

.9025 

.8574 

.9747 

.9830 

.8 

23.04 

110.592 

2.191 

1.687 

1. 

1. 

1. 

.9 

24.01 

117.64? 

2214 

1.690 

1.05 

1.1025 

J58 

!025 

1.016 

5. 

25. 

125. 

2.2361 

1.7100 

1.1 

1.21 

.331 

049 

1.032 

.1 

26.01 

132.651 

2258 

.721 

1.15 

1.3225 

.521 

.072 

1.048 

.2 

27.04 

140.608 

2.280 

.732 

1.2 

1.44 

.728 

.095 

1.063 

.3 

23.09 

148.877 

2.302 

.744 

1.25 

1.5625 

953 

.118 

1.077 

.4 

29.16 

157.464 

2324 

.754 

1.3 

1.69 

2.197 

.140 

1.091 

.5 

30.25 

166.375 

2.345 

.765 

1.35 

1.8225 

2.460 

.162 

.105 

.6 

31.36 

175.616 

2.366 

.776 

1.4 

1.96 

2.744 

.183 

.119 

.7 

32.49 

185  193 

2.387 

.786 

1.45 

2.1025 

3.049 

.204 

132 

.8 

33.64 

195.112 

2408 

.797 

1.5 

2.25 

3.375 

.2247 

.1447 

.9 

34.81 

205.379 

2.429 

.807 

1.55 

2.4025 

3.724 

.245 

.157 

a. 

36. 

216. 

2.4495 

.8171 

1.6 

2.56 

4.096 

.265 

.170 

.1 

37.21 

226.981 

2.470 

.827 

1.65 

2.7225 

4.492 

.285 

.182 

.2 

38.44 

238.328 

2.490 

.837 

1.7 

2.89 

4913 

.304 

.193 

.3 

39.69 

250.047 

2,510 

.847 

1.75 

3.0625 

5.359 

.323 

.205 

.4 

40.96 

262.144 

2530 

.857 

1.8 

3.24 

5.832 

.342 

.216 

.5 

42.25 

274.625 

2.550 

.866 

1.85 

3.4225 

6.332 

.360 

.228 

.6 

43.56 

287.496 

2.569 

1.876 

1.9 

3.61 

6.859 

.378 

.239 

.7 

44.89 

300.763 

2.588 

1.885 

1.95 

3.8025 

7.415 

.396 

.249 

.8 

46.24 

314.432 

2.603 

1.895 

2. 

4. 

8. 

.4142 

.2599 

.9 

47.61 

328.509 

2.627 

1.904 

.1 

4.41 

9.261 

.449 

.281 

7. 

49. 

343. 

2.6458 

1.9129 

.2 

4.84 

10.648 

.483 

.301 

.1 

50.41 

357.911 

2.665 

1.922 

.3 

5.29 

12.167 

.517 

.320 

.2 

51.84 

373.248 

2.683 

1.931 

.4 

5.76 

13.824 

.549 

.339 

.3 

53.29 

389.017 

2.702 

1  940 

.5 

6.25 

15.625 

.581 

.357 

.4 

54.76 

405.224 

2.720 

1.949 

.6 

6.76 

17.576 

.612 

.375 

.5 

56.25 

421.875 

2.739 

1.957 

.7 

7.29 

19.683 

.643 

.392 

.6 

57.76 

438.976 

2.757 

1.966 

,8 

7.84 

21.952 

.673 

.409 

.7 

59.29 

456.533 

2.775 

1.975 

.9 

8.41 

24.389 

.703 

.426 

.8 

60.84 

474.552 

2.793 

1.983 

3. 

9. 

27. 

.7321 

.4422 

.9 

62.41 

493.039 

2.811 

.992 

Republished    by   permission   of  Messrs.   John   Wiley   &  Sons,   Inc. 
from    Kent's   Mechanical   Engineers   Pocket- Book. 


230 


C  ANDREW'S  FLOATING  SCHOOL 


No. 

Square 

Cube. 

Sq. 
Root. 

Cube 
Root. 

No 

Square 

Cube. 

Sq. 

Root. 

Cube 
Root. 

8. 

64. 

512. 

2.8284 

2. 

45 

2025 

9112." 

6.7082  3.ii69 

.1 

65.61 

531.441 

2846 

2.008 

46 

2116 

97336 

6.7823  3  5830 

.2 

67.24 

551.368 

2.864 

2.017 

47 

2209 

103823 

6.65571  3.6088 

.3 

68.89 

571.787 

2.881 

2.025 

43 

2304 

110592 

6.9282 

3.6342 

A 

70.56 

592.704 

2.898 

2.033 

49 

2401 

1  1  7649 

7. 

3.6593 

.5 

72.25 

614.125 

2.915 

2.041 

50 

2500 

125000 

7.0711 

3.6840 

.6 

73.96 

636.056 

2.933 

2.049 

51 

2601 

132651 

7J.414 

3.7084 

.7 

75.69 

653.503 

2.950 

2.057 

52 

2704 

140608 

7.2111 

3.7325 

.8 

77.44 

681.472 

2.966 

2.065 

53 

2309 

143377 

7.2801 

3.7563 

.9 

79.21 

704.969 

2.983 

2.072 

54 

2916 

157464 

7.3485 

3.7798 

9. 

81. 

729. 

3. 

2.0801 

55 

3025 

166375 

7.4162 

3.8030 

.1 

82.81 

753.571 

3.017 

2.088 

56 

3136 

175616 

7.4833 

3.8259 

.2 

84.64 

778.688 

3.033 

2.095 

57 

3249 

185193 

7.5498 

3.8485 

.3 

86.49 

804.357 

3.050 

2.103 

53 

3364 

195112 

7.6158 

3.8709 

.4 

83.36 

830.584 

3.066 

2.110 

59 

3481 

205379 

7,6811 

3.8930 

.5 

90.25 

857.375 

3.082 

2.118 

60 

3600 

216000 

7.7460 

3.9149 

.6 

92.16 

884.736 

3.098 

2.125 

61 

3721 

22698  1 

7.8102 

3.9365 

.7 

94.09 

912.673 

3.114 

2.133 

62 

3344 

238328 

7.8740 

3.9579 

.8 

96.04 

941.192 

3.130 

2.140 

63 

3969 

250047 

7.9373 

3.9791 

.9 

98.01 

970.299 

3.146 

2.147 

64 

4096 

262144 

8. 

4. 

10 

100 

1000 

3.1623 

2.1544 

65 

4225 

274625 

8.0623 

4.0207 

11 

121 

1331 

3.3166 

2.2240 

66 

4356 

287496 

8.1240 

4.0412 

12 

144 

1728 

3.4641 

2.2894 

67 

4489 

300763 

8.1854 

4.0615 

13 

169 

2197 

3.6056 

2.3513 

68 

4624 

3  1  4432 

8.2462 

4.0817 

14 

196 

2744 

3.7417 

2.4101 

69 

4761 

328509 

8.3066 

4.1016 

15 

225 

3375 

3.8730 

2.4662 

70 

4900 

343000 

8.3666 

4.1213 

16 

256 

4096 

4 

2.5198 

71 

5041 

357911 

8.4261 

4.1408 

17 

289 

4913 

4.1231 

2.5713 

72 

5184 

373248 

8.4853 

4.1602 

18 

324 

5832 

4.2426 

2.6207 

73 

5329 

389017 

8.5440 

4.  1  793 

19 

361 

6859 

4.3589 

2.6684 

74 

5476 

405224 

8.6023 

4.1983 

20 

400 

8000 

4.4721 

2.7144 

75 

5625 

421875 

8.6603 

4.2172 

21 

441 

9261 

4.5826 

2.7589 

76 

5776 

438976 

8.7178 

4.2358 

22 

484 

10648 

4.6904 

2.8020 

77 

5929 

456533 

8.7750 

4.2543 

23 

529 

12167 

4.7958 

28439 

78 

6084 

474552 

8.8318 

4.2727 

24 

576 

13824 

4.8990 

2.8845 

79 

6241 

493039 

8.8882 

4.2908 

25 

625 

15625 

5. 

2.9240 

80 

6400 

512000 

8.9443 

4.3089 

26 

676 

17576 

5.0990 

2.9625 

81 

6561 

531441 

9 

4.3267 

27 

729 

19683 

5.1962 

3. 

82 

6724 

551368 

9.0554 

4.3445 

28 

784 

21952 

5.2915 

3.0366 

83 

6839 

571787 

9.1104 

43621 

29 

841 

24389 

5.3852 

3.0723 

84 

7056 

592704 

9.1652 

4.3795 

30 

900 

27000 

5.4772 

3.1072 

85 

7225 

614125 

9.2195 

4.3968 

31 

961 

29791 

5.5678 

3.1414 

86 

7396 

636056 

9.2736 

4.4140 

32 

1024 

32768 

5.6569 

3.1748 

87 

7569 

658503 

9.3276 

4.4310 

33 

1039 

35937 

5.7446 

3.2075 

88 

7744 

631472 

9.3808 

4.446v> 

34 

1156 

39304 

5.8310 

3.2396 

89 

7921 

704969 

9.4340 

4.4647 

35 

1225 

42875 

5.9161 

3.2711 

90 

8100 

729000 

94868 

4.4814 

36 

1296 

46656 

6. 

3.3019 

91 

8281 

753571 

9.5394 

4.4979 

37 

1369 

50653 

6.0828 

3.332; 

92 

8464 

778688 

9.5917 

4.5144 

38 

1444 

54872 

6.1644 

3.3620 

93 

8649 

804357 

96437 

4.5307 

39 

1521 

59319 

6.2450 

3.3912 

94 

8836 

830584 

9.6954 

4.5468 

40 

1600 

64000 

6.3246 

3.4200 

95 

9025 

857375 

9.7468 

4.5629 

41 

1681 

68921 

64031 

3.4482 

96 

9216 

884736 

9.7980 

4.5789 

42 

1764 

74083 

6.4807 

3.4760 

97 

9409 

912673 

98^89 

4.5947 

43 

1849 

79507 

6.5574 

3.5034 

98 

9604 

941  192 

9.8995 

4.6104 

44 

1936 

85184 

6.6332 

3.5303 

99 

9801 

970299 

9  9499 

4.6261 

USEFUL  TABLES  FOR  MARINE  ENGINEERS 


231 


No. 

Sq. 

Cube 

Sq. 
Root. 

Cube 
Root. 

No. 

Square. 

Cube. 

Sq. 
Root. 

Cube 
Root. 

1JJ 

lUJUJ 

1  00000  J 

10. 

4.6416 

155   24C25 

3723875 

12.4499 

5.3717 

131 

10231 

1030301 

10.0499 

4.6570 

156   24336 

3796416 

12.4900 

5.3832 

132 

10434 

1061203 

10.0995 

4.6723 

157 

24649 

3869893 

12.5300 

5  3947 

103 

10609 

1092727 

10.1489 

4.6875 

158 

24964 

3944312 

12.5698 

5  4061 

104 

10316 

1124864 

10.1980 

4.7027 

159 

25281 

4019679 

12.6095 

5.4175 

105 

11025 

1157625 

10.2470 

4.7177 

160 

25600 

4096000 

12.6491 

5.4288 

135 

11236 

1191016 

10.2956 

4.7326 

161 

25921 

4173281 

12.6886 

5.4401 

137 

1  1449 

1225043 

10.3441 

4.7475 

162 

26244 

425  1  528 

12.7279 

5.4514 

133 

11664 

1259712 

10.3923 

4.7622 

163 

26569 

4330747 

12.7671 

5.4626 

139 

11831 

1295029 

10.4403 

4.7769 

164 

26896 

4410944 

12.8062 

5.4737 

110 

12100 

1331000 

10.4881 

4.7914 

165 

27225 

4492  1  25 

12.8452 

5.4848 

111 

12321 

1367631 

10.5357 

4.8059 

166 

27556 

4574296 

12.8841 

5.4959 

112 

12544 

1404923 

10.5830 

4.8203 

167 

27889 

4657463 

12.9228 

5.5069 

113 

12769 

1442397 

10.6301 

4.8346 

168 

28224 

4741632 

12.9615 

5.5178 

114 

12996 

1431544 

10.6771 

4.8488 

169 

28561 

4826809 

13.0000 

5.5288 

115 

13225 

1520375 

10.7238 

4.8629 

170 

28900 

4913000 

13.0384 

5.5397 

115 

13436 

1560396 

10.7703 

4.8770 

171 

29241 

50002  1  1 

13.0767 

5.5505 

117 

13639 

1601613 

10.8167 

4.8910 

172 

29584 

5088448 

13.1149 

5.5613 

113 

13924 

1643032 

10.8628 

4.9049 

173 

29929 

5177717 

13.1529 

5.5721 

119 

14151 

1635159 

10.9087 

4.9187 

.174 

30276 

5268024 

13.1909 

5.5828 

120 

14403 

1  728000 

10.9545 

4.9324 

175 

30625 

5359375 

13.2288 

5.5934 

121 

14641 

1771561 

1  1  .0000 

4.946 

176 

30976 

5451776 

13.2665 

5.6041 

122 

14334 

1815343 

11.0454 

49597 

177 

31329 

5545233 

13.3041 

5.6147 

123 

15129 

1860367 

1  1  .0905 

4.9732 

178 

31684 

5639752 

13.3417 

5.6252 

124 

15376 

1906624 

11.1355 

4.9866 

179 

32041 

5735339 

13.3791 

5.6357 

125 

15625 

1953125 

11.1803 

5.0000 

180 

32400 

5832000 

13.4164 

5.6462 

125 

15376 

2000376 

11.2250 

5.0133 

181 

32761 

5929741 

13.4536 

5.6567 

127 

16129 

2043333 

1  1  .2694 

5.0265 

182 

33124 

6028568 

13.4907 

5.6671 

123 

16334 

2097  1  52 

11.3137 

5.0397 

183 

33489 

6128487 

13.5277 

5.6774 

129 

16641 

2146639 

11.3578 

5.0528 

184 

33856 

6229504 

13.5647 

5.6877 

130 

16930 

2197000 

11.4018 

5.0658 

185 

34225 

6331625 

13.6015 

5.6980 

131 

17161 

224309! 

11.4455 

50788 

186 

34596 

6434856 

13.6382 

5  7083 

132 

17424 

2299963 

11.4891 

5.0916 

187 

34969 

6539203 

13.6748 

5.7185 

133 

17639 

2352637 

11.5326 

5.1045 

188 

35344 

6644672 

13.711315.7287 

134 

17956 

2406104 

11.5758 

5.1172 

189 

35721 

6751269 

13.7477 

5.7388 

135 

18225 

2460375 

11.6190 

5.1299 

190 

36100 

6859000 

13.7840 

5.7489 

136 

18496 

2515456 

11  6619 

5.1426 

191 

36481 

696787  1 

13.8203 

5.7590 

137 

18769 

2571353 

11.7047 

5.155 

192 

36864 

7077888 

13.8564 

5.7690 

133 

19044 

2623072 

11.7473 

5.1676 

193 

37249 

7189057 

13.8924 

5.7790 

139 

19321 

2685619 

11.7898 

5.1801 

194 

37636 

7301384 

13.9284 

5.7890 

140 
141 
H2 

19600 
19331 
20164 

2744003 
2803221 
2363233 

1  1  .8322 
11.8743 
1  1  9164 

5.1925 
5.2048 
5.2171 

195 
196 
197 

38025 
38416 
38809 

7414875 
7529536 
7645373 

13.9642  5.7989 
14.00005.8088 
14.0357l5.8186 

1  H 

20449 

2924207 

11.9583 

5.2293 

198 

39204 

7762392 

14.0712 

5.8285 

144 

20735 

2985934 

12.0000 

5.2415 

199 

39601 

7880599 

14.1067 

5.8383 

145 

21025 

3043625 

120416 

5  2536 

200 

40000 

80000CO 

14.1421 

5.8480 

146 

21316 

3112136 

12'.0830 

5.2656 

201 

40401 

8120601 

14.1774 

5.8578 

147 
143 
149 

21609 
21904 
22201 

3176523 
3241792 
3307949 

12.1244 
12.1655 
12.2066 

5.2776 
5.2896 
5.3015 

202 
203 
204 

40804 
41209 
41616 

8242408 
8365427 
8489664 

14.2127 
14.2478 
14.2829 

5.8675 
5.8771 
5.8868 

150 
151 
152 
153 
154 

22500 
22891 
23104 
23409 
23716 

3375000 
3442951 
3511803 
3581577 
3652264 

12.2474 
12.2882 
12.3288 
12.3693 
12.4097 

5.3133 
5.325 
5.336P 
5.3485 
5.360 

205 
206 
207 
208 
209 

42025 
42436 
42849 
43264 
43681 

8615125 
8741816 
8869743 
8998912 
9129329 

14.3178 
14.3527 
14.3875 
14.4222 
14.4568 

5.8964 
5.9059 
5.9155 
5.9250 
5.9345 

232 


MC  ANDREW'S  FLOATING  SCHOOL 


No. 

Sq. 

Cube. 

Sq. 
Root. 

Cube 
Root. 

No. 

Square. 

Cube. 

Sq. 
Root. 

Cube 
Root. 

210 

44100 

9261000 

14.4914 

5.9439 

^65 

70225 

18609625 

16.2788 

6.4232 

211 

44521 

939393  1 

14.5258 

5.9533 

266 

70756 

18821096 

16.3095 

6.4312 

212 

44944 

9528128 

14.5602 

5.9627 

267 

71289 

19034163 

16.3401 

6.4393 

213 

45369 

9663597 

14.5945 

5.9721 

268 

71824 

19248832 

16.3707 

6.4473 

214 

45796 

9800344 

14.6287 

5.9814 

269 

72361 

19465109 

16.4012 

6.4553 

215 

46225 

9938375 

14.6629 

5.9907 

270 

72900 

19683000 

16.4317 

6.4633 

216 

46656 

10077696 

14.6969 

6.0000 

271 

73441 

19902511 

1  6.462  1 

6.4713 

217 

47089 

10218313 

14.7309 

6.0092 

272 

73934 

20123648 

1  6.4924 

6.4792 

218 

47524 

10360232 

147643 

6.0185 

273 

74529 

20346417 

16.5227 

6.4872 

219 

47961 

10503459 

14.7986 

6.0277 

274 

75076 

20570824 

16.5529 

6.4951 

220 

48400 

10648000 

14.8324 

6.0368 

275 

75625 

20796875 

16.5831 

6.5030 

221 

43341 

10793861 

14.8661 

6.0459 

276 

76176 

21024576 

16.6132 

6.5108 

222 

49234 

10941048 

14.8997 

60550 

277 

76729 

21253933 

16.6433 

65187 

223 

49729 

11039567 

14.9332 

6.0641 

278 

77234 

21434952 

16.6733 

6.5265 

224 

50176 

11239424 

14.9666 

6.0732 

279 

77841 

21717639 

16.7033 

6.5343 

225 

50625 

11390625 

15.0000 

6.0822 

280 

78400 

21952000 

16.7332 

6.5421 

226 

51076 

1154317C 

15.0333 

6.0912 

231 

78961 

22188041 

16.7631 

6.5499 

227 

51529 

11697083 

15.0665 

6.1002 

282 

79524 

22425768 

16.7929 

6.5577 

223 

51934 

11852352 

15.0997 

6.1091 

283 

80089 

22665187 

16.8226 

6.5654 

229 

52441 

12008939 

15.1327 

6.1180 

284 

80656 

22906304 

16.8523 

6.5731 

230 

52900 

12167000 

15.1658 

6.1269 

285 

81225 

23149125 

16.8819 

6.5808 

231 

53361 

1232639! 

15.1937 

6.1358 

286 

81796 

23393656 

16.9115 

6.5885 

232 

53824 

1243716C 

15.2315 

6.1446 

287 

82369 

23639903 

16.9411 

6.5962 

233 

54289 

12649337 

15.2643 

6.1534 

233 

82944 

23887872 

16.9706 

6.6039 

234 

54756 

12812904 

15.2971 

6.1622 

239 

83521 

24137569 

17.0000 

6.6115 

235 

55225 

12977875 

15.3297 

5.1710 

290 

84100 

24389000 

17.0294 

66191 

236 

55696 

1314425C 

15.3623 

6.1797 

291 

84681 

24642171 

17.0587 

6.6267 

237 

56169 

13312053 

15.3948 

6  1885 

292 

85264 

24897088 

17.0880 

6.6343 

238 

56644 

13431272 

15.4272 

6.1972 

293 

85849 

25153757 

17.1172 

6.6419 

239 

57121 

13651919 

15.4596 

6.2058 

294 

86436 

25412184 

17.1464 

6.6494 

240 

57600 

13824000 

15.4919 

6.2145 

295 

87025 

25672375 

17.1756 

6.6569 

241 

53081 

13997521 

15.5242 

6.2231 

296 

87616 

25934336 

17.2047 

6.6644 

242 

53564 

14172483 

15.5563 

6.2317 

297 

83209 

26198073 

17.2337 

6.6719 

243 

59049 

14348907 

15.5885 

6.2403 

293 

88304 

26463592 

17.2627 

6.6794 

244 

59536 

14526784 

15.6205 

6.2488 

299 

89401 

26730899 

17.29  1C 

6.6869 

245 

60025 

14706125 

15.6525 

6.2573 

300 

90000 

27000000 

17.3205 

6.6943 

246 

60516 

14886936 

15.6844 

62658 

301 

90601 

27270901 

17.3494 

6.7018 

247 

61009 

1  5069223 

15.7162 

6.2743 

302 

91204 

27543608 

17.3781 

6.7092 

248 

61504 

15252992 

15.7480 

6.2828 

303 

91809 

27818127 

1  7.4069 

6.7166 

249 

62001 

1  5438249 

15.7797 

6.2912 

304 

92416 

28094464 

17.4356 

6.7240 

250 

62500 

15625000 

15.8114 

6.2996 

305 

93025 

28372625 

1  7.4642 

6.7313 

251 

63001 

15813251 

15.8430 

6.3030 

306 

93636 

23652616  17.4929 

6.7387 

252 

63504 

16003003 

15.8745 

6.3164 

307 

94249 

28934443117.5214 

6.7460 

253 

64009 

16194277 

15.9060 

6.3247 

308 

94864 

292  181  12J  17.  5499 

6.7533 

254 

64516 

16387064 

15.9374 

6.3330 

309 

95481 

29503629 

17.5784 

6.7606 

255 

65025 

16581375 

15.9687 

6.3413 

310 

96100 

29791000 

17.6068 

6.7679 

256 

65536 

16777216 

16.0000 

6.3496 

311 

96721 

300S023  1 

17.6352 

6.7752 

257 

66049 

16974593 

16.0312 

6,3579 

312 

97344 

30371328 

17.6635 

6.7824 

253 

66564 

17173512 

16.0624 

6.3661 

313 

97969 

30664297 

17.6918 

6.7897 

259 

67081 

17373979 

16.0935 

6.3743 

314 

98596 

30959144 

17.7200 

6.7969 

260 

67600 

17576000 

16.1245 

6.3825 

315 

99225 

31255875 

17.7482 

6.8041 

261 

68121 

17779581 

16  1555 

6.3907 

316 

99856 

31554496 

17.7764 

68113 

262 

68644 

1  7984728 

16  1864 

63988 

317 

100489 

31855013 

17.8045 

6.8185 

263 

69169 

18191447 

16.2173 

6.4070 

318 

101124 

32157432117.8326 

6.8256 

264 

69696 

18399744 

16.2481 

6.415 

319 

101761  3246175917.8606 

6.8328 

USEFUL  TABLES  FOR  MARINE  ENGINEERS 


233 


No. 

Square. 

Cube. 

Sq. 
Root. 

Cube 
Root. 

No. 

Square 

Cube. 

Sq. 
Root. 

Cube 
Rcot. 

320 
321 

102400 
103041 

32768000 
33076161 

1  7.8885  J6.8399 
17.91656.8470 

^375 
376 

140625 
141376 

52734375 
53157376 

19.3649 
19.3907 

7.2112 
7.2177 

322 

103684 

33386248 

17.94446.8541 

377|I42129 

53582633 

19.4165 

7^2240 

323 

104329 

33698267 

17.9722 

6.8612 

378 

142884 

54010152 

19.4422 

7  2304 

324 

104976 

34012224 

18.00006.8683 

379 

143641 

54439939 

19.4679 

7J368 

325 

105625 

34328125 

18.02786.8753 

380 

1  44400 

54872000 

1  9.4936 

72432 

326 

106276 

34645976 

18.0555 

6.8824 

381 

145161 

55306341 

19.5192 

7  2495 

327 

1  06929 

34965783 

18.0831 

6.8894 

382 

145924 

55742968 

19  5448 

7.2558 

328 

107584 

35287552 

1  8.  1  1  08  6.8964 

383 

1  46689 

56181887 

19.5704 

7  2622 

329 

108241 

35611289 

18.1384 

6.9034 

384 

147456 

56623104 

19.5959 

7.2685 

330 

108900 

35937000 

18.1659 

6.9104 

385 

148225 

57066625 

19.6214 

72748 

331 

109561 

36264691 

18.1934i6.9174 

386 

148996 

57512456 

19.6469 

7.2811 

332 

110224 

36594368 

18.2209 

6.9244 

387 

1  49769 

57C60603 

19  6723 

7  2874 

333 

110889 

36926037J  18.2483  6.9313 

383 

1  50544 

58411072 

19.6977 

7.2936 

334 

111555 

37259704 

18.2757 

6.9382 

389 

151321 

58863869 

19.7231 

7.2999 

335 

336 

112225 
112896 

37595375 
37933056 

18.3030 
18.3303 

6.9451 
6.9521 

390 
391 

152100 
152881 

593  1  9000 
59776471 

1  9.7484 
19.7737 

7.3061 
7.3124 

337 

113569 

38272753 

18.3576 

6.9589 

392 

153664 

60236288 

19.7990 

7.3166 

338 

114244 

38614472 

18.3848 

6.9658 

393 

1  54449 

60598457 

19.8242 

73248 

339 

114921 

38958219 

18.4120 

6.9727 

394 

155236 

61162984 

19.8494 

7.3310 

340 

1  1  5600 

39304000 

18.4391 

6.9795 

395 

156025  61629875 

19.8746 

7.3372 

341 

116281 

39651821 

1  8.4662 

6.9864 

5% 

156816  62099136 

19.8997 

7.3434 

342 

116964 

4000  168S 

18.4932 

6.9932 

397 

157(09 

62570773 

19.9249 

7.3496 

343 

1  1  7649 

40353607 

18.5203 

7.0000 

398 

158404 

63044792 

19.9499 

7.35*8 

344 

118336 

40707584 

18.5472 

7.0068 

399 

159201 

63521199 

19.9750 

7.3619 

345 

119025 

41063625 

18.5742 

7.0136 

400 

160000 

64000000 

20.CCOO 

7.3681 

346 

119716 

41421736 

18.6011 

7.0203 

401 

leoeoi 

64481201  20.0250 

7  3742 

347 

120409 

41781923 

18.62797.0271 

402 

161(04 

64964808120.0499 

7.3803 

348 

121104 

42144192 

18.6548 

7.0338 

403 

162  -'09 

65450627 

20.0749 

7.3864 

349  121801 

42508549 

18.6815 

7.0406 

404 

163216 

65939264 

20.0998 

7.3925 

350  122500 

42875000 

18.7083 

7.0473 

405 

164025 

66430125 

20.1246 

7.3986 

351  123201 

43243551 

18.7350 

7.0540 

406 

164836 

€6923416 

20.1494 

7.4047 

352  123904 

436  1  4208 

18.7617 

7.0607 

407 

165649 

6741914320.1742 

7.4108 

353  124609 

43986977 

18.7883 

7.0674 

403 

166464 

67917312120.1990 

7.4169 

354  125316 

44361864 

18.8149 

7.0740 

409 

167281 

68417929 

20.2237 

7.4229 

355|  126025 

44738875 

18.8414 

7.0807 

410 

168100 

68921  COO 

20  2485 

74290 

356  126736 

45118016 

18.8680 

7.0873 

411 

168921 

69426531 

20.2731 

7.4350 

357,  127449 

45499293 

1  8  8944 

70940 

412 

169744 

69934528 

20.2978 

7.4410 

358  128164 
359  128881 

45882712 
46263279 

1892097  1006 
18.9473  7!  1072 

413 
414 

1  70569 
171396 

70444997 
70957944 

20.3224 
20.3470 

7.4470 
7.4530 

360 

129600 

46656000 

189737 

7.1138 

415 

172225 

7147337520.3715 

7.4590 

361  130321 

47045881 

19.0000 

7.1204 

4!6 

173056 

7199129620.3961 

7.4650 

362  131044 

47437928 

19.0263 

7.1269 

417 

1738S9 

7251171320.4206 

7.4710 

363  131769 

47832147 

19.0526 

7  1335 

418 

174724 

73034632  20.4450 

7.4770 

364 

132496 

48228544 

19.0788 

7.1400 

419 

175561 

73560059 

20.4695 

7.4829 

365  133225 

48627125 

19  1050 

7.1466 

420 

1  76400 

74088000 

20.4939 

7.4889 

366  133956 

49027896 

19.1311 

7.1531 

421 

177241 

74618461 

20.5183 

7.4948 

367  134689 

49430863 

19.1572 

7.1596 

422 

1  78084 

75151448 

20.5426 

7.5C07 

368  135424 

49836032 

19.1833 

7.1661 

423 

1  78929 

75686967  20.5670 

7.5067 

369 

136161 

50243409 

19.2094 

7.1726 

424 

1  79776 

76225024 

20.5913 

7.5126 

370 

1  36900 

50653000 

192354 

7.1791 

425 

180625 

76765625 

20.6155 

7.5185 

371  137641  51064811 

192614 

7.1855 

426 

18'476 

7730877620.6398 

7.5244 

372 

138384  51478848 

19.2873 

7.1920 

427 

182329 

77854483  20.6640 

7.5302 

373 

139129  51895117 

19.3132 

7.1984 

428 

183184  7840275220.6882 

7.5361 

374  139876  52313624 

19.3391 

7.2048 

429 

184041  7895358920.7123  7.5420 

234 


MC   ANDREW'S   FLOATING   SCHOOL 


No. 
430 

Square 

Cube. 

Sq. 
Root. 

Cube 
Root. 

No. 

Square 

Cube. 

Sq. 
Root. 

Cube 
Root. 

184900 

79507000 

20.7364  7.5478 

485 

235225 

114084125 

22.0227 

7.8563 

431 

185761 

80062991 

20.76057.5537 

486 

236196 

114791256 

22.0454 

7  8622 

432 

186624 

80621568 

20.7846'7.5595 

487 

237169 

115501303 

220681 

7  8676 

433 

187489 

81182737 

20.8087 

7.5654 

488 

238144 

116214272122.0907 

7.8730 

434 

188356 

81746504 

20.8327 

7.5712 

489 

239121 

116930169 

22.1133 

7.8784 

435 

139225 

82312875 

20.8567 

7.5770 

490 

240100 

1  1  7649000 

22.1359 

7.8837 

436 

1  90096 

82831856 

20  8806 

7.5828 

491 

241081 

118370771 

22.1585 

7.8891 

437 

190969 

83453453 

20.9045 

7.5886 

492 

242064 

119095488 

22.1811 

7.8944 

438 

191844 

84027672 

20.9284 

7.5944 

493 

243049 

119823157 

22.2036 

7.8998 

439 

192721 

846045  1  9 

20.9523 

7.6001 

494 

244036 

120553784 

22.2261 

7.9051 

440 

193600 

85184000 

20.9762 

7.6059 

495 

245025 

121287375 

22.2486 

7.9105 

441 

194481 

85766121 

21.0000 

7.6117 

496 

246016 

122023936 

22.2711 

7.9153 

442 

195364 

86350888 

21  .0238 

7.6174 

497 

247009 

122763473 

22.2935 

7.9211 

443 

196249 

86938307 

21  0476 

7.6232 

498 

248004 

123505992 

22.3159 

7.9264 

444 

197136 

87528384 

21.0713 

7.6289 

499 

249001 

124251499 

22.3383 

7.9317 

445 

198025 

88121125 

21.0950 

7.6346 

500 

250000 

125000000 

22.3607 

7.9370 

446 

198916 

88716536 

21.1187 

7.6403 

501 

251C01 

125751501 

22.3830 

7.9423 

447 

199309 

893  1  4623 

21.1424 

7.6460 

502 

257C04 

126506008 

22  4054 

7.9476 

443 

200704 

89915392 

21.1660 

7.6517 

5u3 

253009 

127263527 

22.4277 

7.9523 

449 

201601 

90518849 

21.1896 

7.6574 

504 

254016 

128024064 

22.4499 

7.9581 

450 

202500 

91125000 

21.2132 

7.6631 

505 

255025 

128787625 

22.-'.722 

7.9634 

451 

203401 

91733851 

21.2368 

7.6688 

506 

256036 

129554216 

22.4944 

7.9686 

452 

204304 

92345408 

21.2603 

7.6744 

507 

257049 

130323843 

22.5167 

79739 

453 

205209 

92959677 

21.2838 

7.6800 

508 

258064 

131096512 

22.5389 

7.9791 

454 

206116 

93576664 

21.3073 

7.6857 

509 

259081 

131872229 

22.5610 

7-9843 

455 

207025 

94196375 

21.3307 

7.6914 

510 

260100 

132651000 

22.5832 

7.9896 

456 

207936 

94818816 

21.3542 

7.6970 

511 

261121 

133432331 

22.6053 

7.9948 

457 

203849 

95443993 

21.3776 

7.7026 

512 

262144 

134217728 

22.6274 

8.COOO 

458 

209764 

96071912 

2  1  .4009 

7.7082 

513 

263169 

1  35005697 

22.6495 

8.0052 

459 

210681 

96702579 

21.4243 

7.7138 

514 

264196 

135796744 

22.6716 

8.0104 

<60 

211600 

97336000 

21.4476 

7.7194 

515 

265225 

136590875 

22.6936 

8.0156 

461 

212521 

97972181 

21.4709 

7.7250 

516 

266256 

137388096 

22.7156 

8.0208 

462 

213444 

98611128 

21.4942 

7.7306 

517 

267289 

138138413 

22.7376 

8.0260 

463 

214369 

99252847 

21.5174 

7.7362 

518 

268324 

138991832 

22.7596 

8.0311 

464 

215296 

99897344 

21.5407 

7.7418 

519 

269361 

139798359 

22.7816 

8.0363 

465 

216225 

100544625 

21.5639 

7.7473 

520 

270400 

140608000 

22.8035 

8.0413 

466 

217156 

101194696 

21.5870 

7.7529 

521 

271441 

141420761 

22.8254 

8.0466 

467 

218039 

101847563 

21.6102 

7.7584 

522 

272484 

142236648 

22.8473 

8.0517 

468 

219024 

102503232 

21.6333 

7.7639 

523 

273529 

143055667 

22.8692 

80569 

469 

219961 

103161709 

21.6564 

7.7695 

524 

274576 

143877824 

22.8910 

8.0620 

470 

220900 

103823000 

21.6795 

7.7750 

525 

275625 

144703125 

22.9129 

8.0671 

471 

221341 

104437111 

21.7025 

7.7805 

526 

276676 

145531576 

22.9347 

8.0723 

472 

222734 

105154048 

21.7256 

7.7860 

527 

277729 

146363183 

22.9565 

8.0774 

473 

223729 

105823317 

21.7486 

7.7915 

528 

278784 

147197952 

22.9783 

8.0825 

474 

224576 

106496424 

21.7715 

7.7970 

529 

279841 

148035889 

23.0000 

8.0876 

475 

225625 

107171875 

21  7945 

7.8025 

530 

280900 

148877000 

23.0217 

8.0927 

476 

226576 

107850176 

21.8174 

7.8079 

531 

281961 

149721291 

23.0434 

8.0978 

477 

227529 

108531333 

21.8403 

7.8134 

532 

283024 

1  50568768 

23.0651 

8.1028 

478 

228484 

109215352 

21  8632 

7.8188 

533 

284089 

151419437 

23.0868 

8.1079 

479 

229441 

109902239 

2K8861 

7.8243 

534 

285156 

152273304 

23.1084 

8.1130 

480 

230400 

1  1  0592000 

21.9089 

7.8297 

535 

286225 

153130375 

23.1301 

8.1180 

481 

231361 

111284641 

21.9317 

7.8352 

536 

287296 

1  53990656 

23.1517 

8.1231 

482 

232324 

111980168 

21.9545 

7.8406 

537 

288369 

154854153 

23.1733 

8.1281 

483 

233289 

112678587 

21.9773 

7.8460 

538 

289444 

155720872 

23.1948 

8.1332 

484 

234256 

1  13379904 

22.0000 

7.8514 

539 

290521 

156590319 

23.2164 

8.1382 

USEFUL  TABLES  FOE  MARINE  ENGINEERS 


235 


No. 

540 
541 
542 
543 
544 

Square. 

Cube. 

Sq. 
Root. 

Cube 
Root. 

No. 

Square 

Cube. 

Sq. 
Root. 

Cube 
Root. 

29  1  600 
292681 
293764 
294349 
295936 

157464000 
158340421 
1  59220083 
160103007 
160989184 

23.2379 
23.2594 
23.2809 
23.3024 
23.3238 

8.1433 
8.1483 
8.1533 
8.1583 
8.1633 

595 
596 
597 
598 
599 

354025 
355216 
356409 
357604 
358801 

2106448/5 
211708736 
212776173 
213847192 
214921799 

24.3926 
24.4131 
24.4336 
24.4540 
24.4745 

8.4108 
8.4155 
8.4202 
8.4249 
8.4296 

545 

546 
547 
543 
549 

297025 
298116 
299209 
300304 
301401 

161378625 
162771336 
163667323 
164566592 
165469149 

23.3452 
23.3666 
23.3880 
23.4094 
23.4307 

8.1683 
8.1733 
8.1783 
8.1833 
8.1882 

600 
601 
602 
603 
604 

360000 
361201 
362404 
363609 
364816 

216000000 
217081801 
218167208 
219256227 
220348864 

24.4949 
24.5153 
24.5357 
24.5561 
24.5764 

8.4343 
8.4390 
8.4437 
8.4484 
8.4530 

550 
551 
552 
553 
554 

302500 
303601 
304704 
305809 
306916 

166375000 

167234151 
163196608 
169112377 
170031464 

23.4521 
23.4734 
23.4947 
23.5160 
23.5372 

8.1932 
8.1982 
8.2031 
8.2081 
8.2130 

605 
606 
607 
608 
609 

366025 
367236 
363449 
369664 
370881 

221445125 
222545016 
223648543 
224755712 
225866529 

24.5967 
24.6171 
24.6374 
24.6577 
24.6779 

8.4577 
8.4623 
8.4670 
8.4716 
8.4763 

555 
556 
557 

553 
559 

308025 
309136 
310249 
3  1  1  364 
312481 

170953875  23.5584 
17187961623.5797 
172803693  23.6003 
173741112  23.6220 
17467687923.6432 

8.2180 
8.2229 
8.2278 
8.2327 
8.2377 

610 
611 
612 
613 
614 

372100 
373321 
374544 
375769 
376996 

226981000 
228099131 
229220928 
230346397 
231415544 

24.6982 
24.7184 
24.7386 
24.7588 
24.7790 

8.4809 
8.4856 
8.4902 
8.4948 
8.4994 

560 
561 
D62 
563 
564 

313600  17561600023.6643 
314721  176553431:23.6354 
3  1  5844:  1  77504323  23.7065 
3  1  6969  1  78453547  23.7276 
318096  17940614423.7487 

8.2426 
8.2475 
8.2524 
8.2573 
8.2621 

615 
616 
617 
618 
619 

378225 
379456 
380639 
381924 
383161 

232608375 
233744896 
234885113 
236029032 
237176659 

24.7992 
24.8193 
24.8395 
24.8596 
24.8797 

8.5040 
8.5086 
8.5132 
8.5178 
8.5224 

565 
566 
'>67 
568 
569 

319225 

320356 
321489 
322624 
323761 

180362125  23.7697 
18132149623.7903 
182234263  23.0118 
1P3250432  23.8323 
.8422000923.8537 

8.2670 
8.2719 
8.2763 
8.2816 
8.2865 

620 
621 
622 
623 
624 

384400 
385641 
336884 
383129 
389376 

238328000 
239483061 
240641848 
241804367 
242970624 

24  8998 
249199 
24.9399 
24.9600 
24.9800 

8.5270 
8.5316 
8.5362 
8.5408 
8.5453 

570 
571 
572 
573 
574 

324900 
326041 
327184 
328329 
329476 

18519300023.8747 
186169411  23.8956 
187149243:23.9165 
18313251723.9374 
18911922423.9583 

8.2913 
8.2962 
8.3010 
8.3059 
8.3107 

625 
626 
627 
628 
629 

390625 
391876 
393129 
394384 
395641 

244140625 
245314376 
246491833 
247673152 
248858189 

25.0000 
25.0200 
25.0400 
25.0599 
25.0799 

8.5499 
8.5544 
85590 
8.5635 
8.5681 

575 
576 

577 
578 
579 

330625 
331776 
332929 
334084 
335241 

190109375 
191102976 
192100033 
193100552 
194104539 

23.9792 
24.0000 
24.0208 
24.0416 
24.0624 

8.3155 
8.3203 
8.3251 
8.3300 
8.3348 

630 
631 
632 
633 
634 

396900 
398161 
399424 
400639 
401956 

250047000 
251239591 
252435968 
253636137 
254840104 

25.0998 
25.1197 
25.1396 
25.1595 
25.1794 

8.5726 
8.5772 
8.5817 
8.5862 
8.5907 

580 
581 
582 
583 
584 

336400 
337561 
338724 
339889 
341056 

195112000 
196122941 
197137368 
193155287 
199176704 

24.0832 
24.1039 
24.1247 
24.  1  454 
24.1661 

8.3396 
8.3443 
8.3491 
8.3539 
8.3587 

635 
636 
637 
638 
639 

403225 
404496 
405769 
407044 
40832  1 

256047875 
257259456 
258474853 
259694072 
260917119 

25.1992 
25.2190 
25.2389 
25.2587 
25.2784 

8.5952 
8.5997 
8.6043 
8.6083 
8.6132 

585 

536 
587 
533 
589 

342225 
343396 
344569 
345744 
34692  1 

200201625 
201230056 
202262003 
203297472 
204336469 

24.1868 
24.2074 
24.2281 
24.2437 
24.2693 

8.3634 
8.3682 
8.3730 
8.3777 
8.3825 

640 
641 
642 
643 
644 

409600 
410881 
412164 
413449 
414736 

262144000 
263374721 
264609288 
265847707 
267089934 

25.2982 
25.3180 
25.3377 
25.3574 
25.37>2 

8.6177 
8.6222 
8.6267 
8.6312 
8.6357 

590 
591 
592 
593 
594 

343100 
349281 
350464 
351649 
352836 

205379000 
206425071 
207474688 
208527857 
209584584 

24.2899 
243105 
24.331  1 
24.3516 
24.3721 

8.3872 
8.3919 
8.3967 
8.4014 
8.4061 

645 
646 
647 
648 
649 

416025 
417316 
418609 
419904 
421201 

268336125 
269586136 
270840n?3 
272097792 
273359449 

25.3969 
25.4165 
25.4362 
25.4558 
254755 

8.6401 
8.6446 
86490 
86535 
8.6579 

236 


MC  ANDREW'S  FLOATING  SCHOOL 


No. 

650 
651 
652 
653 
654 

Square. 

422500 
423801 
425104 
426409 
427716 

Cube. 

Sq. 
Root. 

Cube 
Root. 

No. 

~705 
706 
707 
708 
709 

Square 

Cube. 

Sq. 
Root. 

Cube 
Root. 

274625000 
27  389445  1 
277167808 
278445077 
279726264 

25.4951 
25.5147 
25.5343 
25.5539 
25.5734 

8.6624 
8.6668 
8.6713 
8.6757 
8.6801 

497025 
498436 
499849 
501264 
502681 

350402625 
351895816 
353393243 
354894912 
356400829 

26.5518 
26.5707 
26.5895 
26.6083 
26.6271 

8.9001 
8.9043 
8.9085 
8.9127 
8.9169 

655 
656 
657 
658 
659 

429025 
430336 
431649 
432964 
434281 

281011375 
282300416 
283593393 
284890312 
286191179 

25.5930 
25.6125 
25.6320 
25.6515 
25.6710 

8.6845 
8.6890 
8.6934 
8.6978 
8.7022 

710 
711 
712 
713 
714 

504100 
505521 
506944 
508369 
509796 

357911000 
359425431 
360944128 
362467097 
363994344 

26.6458 
26.6646 
26.6833 
26.7021 
26.7208 

8.9211 
8.9253 
8.9295 
8.9337 
8.9378 

660 
661 
662 
663 
664 

435600 
43692  1 
438244 
439569 
440896 

287496000 
288804781 
290117528 
291434247 
292754944 

25.6905 
25.7099 
25.7294 
25.7483 
25.7682 

8.7066 
8.7110 
8.7154 
8.7198 
8.7241 

715 
716 
717 
718 
719 

511225 
512656 
5  1  4089 
515524 
516961 

365525875 
367061696 
366601813 
370146232 
371694959 

26.7395 
26.7582 
26.7769 
26.7955 
26.8142 

8.9420 
8.9462 
8.9503 
8.9545 
8.9587 

665 
666 
667 
663 
669 

442225 
443556 
444889 
446224 
447561 

294079625 
295408296 
296740963 
298077632 
299418309 

25.7876 
25.8070 
25  8263 
25.8457 
25.8650 

8.7285 
o.7329 
87373 
8.  7<  16 
8.7460 

720 

721 
722 
723 
724 

518400 
519841 
521284 
522729 
524176 

373248000 
374805361 
376367048 
377933067 
379503424 

26.8328 
26.8514 
26.8701 
26.8887 
26.9072 

8.9628 
8.9670 
8.9711 
8.9752 
8.9794 

670 
671 
672 
673 
674 

448900 
450241 
451584 
452929 
454276 

300763000 
302111711 
303464448 
304821217 
306182024 

25.8844 
25.9037 
25  9230 
25.9422 
25.9615 

8.7503 
8.7547 
8.7590 
3.7634 
8.7677 

725 
726 
727 
728 
729 

525625 
527076 
528529 
529984 
531441 

381078125 
382657176 
384240583 
385828352 
387420489 

26.9258 
26  9444 
26.9629 
26.9815 
27.0000 

8.9835 
8.9876 
8.9918 
8.9959 
90000 

675 
676 
677 
678 
679 

455625 
456976 
458329 
459684 
461041 

307546875 
308915776 
310288733 
311665752 
313046839 

25.9803 
26  0000 
26.0192 
26.0384 
26.0576 

8.7721 
87764 
8.7807 
8.7850 
8.7893 

730 
731 
732 
733 
734 

532900 
534361 
535824 
537289 
538756 

389017000 
390617891 
392223168 
393832837 
395446904 

27.0185 
27.0370 
27.0555 
27.0740 
27.0924 

9.0041 
9.0082 
9.0123 
9.0164 
9.0205 

680 
681 
682 
683 
684 

462400 
463761 
465124 
466489 
467856 

314432000 
315821241 
317214569 
318611987 
320013504 

26.0768 
26  0960 
26.1151 
26.1343 
26.1534 

8.7937 
87980 
8.8023 
8.8066 
8.8109 

735 
736 
737 
733 
739 

540225 
541696 
543  1  69 
544644 
546121 

397065375 
398688256 
400315553 
401947272 
403583419 

27.1109 
27.1293 
27.1477 
27.1662 
27.1846 

9.0246 
9.0287 
9.0328 
90369 
9.0410 

685 
686 
687 
688 
689 

469225 
470596 
47  1  969 
473344 
474721 

321419125 
322828856 
324242703 
325660672 
327082769 

26.1725 
26  1916 
26.2107 
26.2298 
26.2488 

88152 
88194 
8.8237 
88280 
8.8323 

740 
741 
742 
743 
744 

547600 
54908  1 
550564 
552049 
553536 

40522400C 
406869021 
408518488 
410172407 
411830704 

27.2029 
27.2213 
27.2397 
27.2560 
27.2764 

9.0450 
90491 
9.0532 
9.0572 
9.0613 

690 
691 
692 
693 
694 

476100 
477481 
478364 
480249 
481636 

328509000 
329939371 
331373888 
332812557 
334255384 

26  2679 
26.2869 
26.3059 
26.3249 
26.3439 

8.8366 
6.8408 
88451 
8.8493 
8.8536 

745 
746 
747 
74S 
749 

555025 
556516 
558009 
559504 
561001 

413493625 
415160936 
416832723 
418508992 
420189749 

27  2947 
27.3130 
27.3313 
27.3496 
27.3679 

9.0654 
9.0694 
90735 
9.0775 
9.0816 

695 
696 
697 
693 
699 

483025 
484416 
485809 
487204 
488601 

335702375 
337153536 
338608873 
340068392 
341532099 

26.3629 
26.3818 
26.4008 
26.4197 
26.4386 

8.8578 
8.8621 
8.8663 
8.8706 
8.8748 

750 
751 
752 
753 
754 

562500 
564001 
565504 
567009 
5685  1  6 

4218750CO 
423564751 
425259008 
42695777/ 
428661061 

273861 
27.404< 
27.4226 
27.4408 
27.4591 

9.0856 
90896 
9.0937 
9.0977 
9.1017 

700 
701 
702 
703 
704 

490000 
491401 
492804 
494209 
495616 

343000000 
344472101 
345948408 
347428927 
348913664 

26.4575 
26  4764 
264953 
26.5141 
765330 

8.8790 
88833 
88875 
88917 
88959 

755 
756 
757 
758 
759 

570025 
571536 
573049 
574564 
576081 

430368875 
432081216 
433798093 
435519512 
437245479 

27.4/73 
27.4955 
27  5136 
27.5318 
27.5500 

91057 
9  1098 
9.1138 
9  1178 
9.1218 

USEFUL  TABLES  FOR  MARINE  ENGINEERS 


237 


No 

760 
76 
762 
763 
764 

Square 

Cube. 

Sq. 
Root. 

Cube 
Root. 

No. 

Square 

Cube. 

Sq. 
Root. 

Cube 
Root. 

57/60U 
579121 
580644 
532169 
533696 

438976000 
J4407I1081 
442450728 
444194947 
445943744 

27.5681 
27.5862 
27.6043 
27.6225 
27.6405 

9.1258 
9.1298 
9.1338 
9.1378 
9.1418 

815 
816 
817 
818 
819 

664225 
665856 
667489 
669124 
670761 

541343375 
543338496 
545338513 
547343432 
549353259 

28.5482 
28.5657 
28.5832 
28.6007 
28.6182 

9.3408 
9.3447 
9.3485 
9.3523 
9.3561 

765 
766 
767 
763 
769 

535225 
536736 
533289 
539324 
591361 

447697125 
449455096 
451217663 
452984832 
454756609 

27.6586 
27.6767 
27.6948 
27.7128 
27.7308 

9.1458 
9.1498 
9.1537 
9.1577 
9.1617 

820 
821 
822 
823 
824 

672400 
674041 
675684 
677329 
678976 

551368000 
553387661 
555412248 
557441767 
559476224 

28.6356 
28.6531 
28.6705 

28.688C 
28.7054 

9.3599 
9.3637 
9.3675 
9.3713 
9.3751 

770 
771 
772 
773 
774 

592903 
594441 
595984 
597529 
599076 

456533000 
458314011 
460099648 
461889917 
463684824 

27.7489 
27.7669 
27.7849 
27.8029 
27.8209 

9.1657 
9.1696 
9.1736 
9.1775 
9.1815 

825 
826 
827 
823 
829 

680625 
632276 
633929 
685584 
687241 

561515625 
563559976 
565609283 
567663552 
569722789 

28.7228 
28.7402 
28.7576 
28.775C 
28.7924 

9.3789 
9.3827 
9.3865 
9.3902 
9.3940 

775 

776 
777 
778 
779 

630625 
632176 
633729 
635234 
636341 

465434375 
467283576 
469097433 
470910952 
472729139 

27.8383 
27.8563 
27.8747 
27.8927 
27.9106 

9.1855 
9.1894 
9.1933 
9.1973 
9.2012 

830 
831 
832 
833 
834 

688900 
690561 
692224 
693889 
695556 

571787000 
573856191 
575930368 
578009537 
580093704 

28.8097 
28.8271 
28.8444 
28.8617 
28.8791 

9.3978 
9.4016 
9.4053 
9.4091 
9.4129 

733 
731 
782 
733 
784 

603403 
639961 
611524 
613039 
614656 

474552000 
476379541 
478211763 
430043637 
431890304 

27.9285 
27.9464 
27.9643 
27.9821 
28.0000 

9.2052 
9.2091 
9.2130 
9.2170 
9.2209 

835 
836 
837 
833 
839 

697225 
698896 
700569 
702244 
703921 

582182875 
584277056 
586376253 
588480472 
590589719 

28.8964 
28.9137 
28.9310 
28.9482 
28.9655 

9.4166 
9.4204 
9.4241 
9.4279 
9.4316 

785 

786 
787 
733 
739 

616225 
617796 
619369 
620944 
622521 

483736625 
435537656 
437443403 
439303372 
491169069 

28.0179 
28.03  7 
28.0535 
23.0713 
28.0891 

9.2243 
9.2287 
9.2326 
9.2365 
9.2404 

840 
841 
842 
843 
844 

705600 

707281 
708964 
710649 
712336 

592704000 
594323321 
596947688 
599077107 
601211584 

28.9828 
29.0000 
29.0172 
29.0345 
29.0517 

9.4354 
9.4391 
9.4429 
9.4466 
9.4503 

793 

791 
792 
793 
794 

624100 
625631 
627264 
623349 
630436 

493039000 
494913*71 
496793083 
493677257 
500566184 

28.1069 
28.1247 
28.1425 
23.1603 
28.  1  780 

9.2443 
9.2482 
9.2521 
~.2560 
9.2599 

845 
846 
847 
843 
849 

714025 
715716 
717409 
719104 
720801 

603351125 
605495736 
607645423 
609800192 
611960049 

29.0689 
29.0861 
29.1033 
29.1204 
29.1376 

9.4541 
9.4578 
9.4615 
9.4652 
9.4690 

795 
796 
797 
793 
799 

632025 
633616 
635209 
636304 
638401 

502459875 
504353336 
5062:1573 
508160592 
510082399 

28.1957 
28.2135 
28.2312 
28.2489 
28.2666 

9.2638 
9.2677 
9.2716 
9.2754 
9.2793 

850 
851 
852 
853 
854 

722500  614125000  29.1548 
724201  616295051  29.1719 
725904  618470208  29.1890 
727609  620650477;  29.2062 
7293  1  6  622835864  29.2233 

9.4727 
9.4764 
9.4301 
9.-+83S 
9.4875 

800 
801 
802 
803 
804 

640000  5  1  2000000 
641601  513922401 
643204  515849608 
644809  517781627 
646416519718464 

28.2843 
28.3019 
28.3196 
28.3373 
28.3549 

9.2832 
9.2870 
9.2909 
9.2948 
9.2986 

855  7310251 
856  732736 
857  734449 
858  736164 
859  737881 

625026375  29.2404 
62722201629.2575 
629422793  29.2746 
63162871229.2916 
633839779  29.3087 

9.4912 
9.4949 
9.4986 
9.5023 
9.5060 

805 
806 
807 
808 
809 

643025 
649636 
651249 
652864 
654431 

52166012528.37259.3025 
523606616  28.3901  9.3063 
525557943  28.4077  9.3102 
52751411228.42539.3140 
52947512928.44299.3179 

860  739600  636056000 
861  741321  638277381 
862  743044  640503928 
863  744769  642735647 
864  746496  644972544 

29.3258 
29.3428 
29.3598 
29.3769 
29.3939 

9.5097 
9.5134 
9.5171 
9.5207 
9.5244 

810 
811 
812 
813 
814 

656100 
657721 
659344 
660969 
662596 

53144100028.46059.3217 
533411  73  1;28.4781  9.3255 
535387328*28.4956  9.3294 
537367797!28.5132  9.3332 
539353  1  441  28.5307  9.3370 

865 
866 
867 
868 
869 

748225  647214625  29.4109 
749956  649461896  29.4279 
751689651714363:29.4449 
75342465397203229.4618 
755  161  1656234909129.4783 

9.5231 
9.5317 
9.5354 
9.5391 
9.5427 

238 


MC  ANDREW'S  FLOATING  SCHOOL 


No 

Square 

Cube. 

Sq. 
Root. 

Cube 
Root  . 

Xo. 

^925 
926 
927 
928 
929 

Square 

Cube. 

Sq. 
Root. 

Cube 
Root. 

870 

87! 
872 
873 
874 

756900 
758641 
760384 
762  1  29 
763876 

658503000 
6607763  1  1 
603054848 
665338617 
667627624 

29.4958 
29.5127 
29.5296 
29.5466 
29.5635 

9.5464 
9.5501 
9.5537 
9.5574 
9.5610 

855625 
857476 
859329 
861184 
863041 

791453125 
794022776 
796597983 
799178752 
801765089 

30.4138 
30.4302 
30.4467 
30.4631 
30.4795 

9.7435 
9.7470 
9.7505 
9.7540 
9.7575 

875 
876 
877 
878 
879 

765625 
767376 
769129 
770884 
772641 

669921875 
672221376 
674526133 
676836152 
679151439 

29.5804 
29.5973 
29.6142 
29.63  1 
29.6479 

9.5647 
9.5683 
9.5719 
9.5756 
9.5792 

930 
931 
932 
933 
934 

864900 
866761 
868624 
870489 
872356 

S0435700C 
806954491 
809557568 
812166237 
814780504 

30.4959 
30.5123 
30.5287 
30.5450 
30.5614 

9.7610 
9.7645 
9.7680 
9.7715 
9.7750 

880 
881 
882 
883 
884 

774400 
776161 
777924 
779689 
781456 

681472000 
683797841 
686128968 
688465387 
690807104 

29.6648 
29.6816 
29.6985 
29.7153 
29.7321 

9.5828 
9.5865 
9.5901 
9.5937 
9.5973 

935 
936 
937 
938 
939 

874225 
876096 
877969 
879844 
881721 

817400375 
820025856 
822656953 
825293672 
827936019 

30.5778 
30.5941 
30.6105 
30.6263 
30.6431 

9.7785 
9.7819 
9.7854 
9.7889 
9.7924 

885 

886 
887 
883 
889 

783225 
784996 
786769 
788544 
790321 

693154125 
695506456 
697864103 
700227072 
702595369 

29.748? 
29.7658 
29.7825 
29.7993 
29.8161 

9.6010 
9.6046 
9.6082 
9.6118 
9.6154 

940 
941 
942 
943 
944 

833600 
835481 
837364 
839249 
891136 

830584000 
833237621 
835896888 
838561807 
841232384 

30.6594 
30.6757 
30.6920 
30.7083 
30.7246 

9.7959 
9.7993 
9.8028 
9.8063 
9.8097 

890 
891 
892 
893 
894 

792100 
793881 
795664 
797449 
799236 

704969000 
707347971 
709732288 
712121957 
714516984 

29.8329 
29.8496 
29.8664 
29.883  1 
29.8998 

9.6190 
9.6226 
9.6262 
9.6298 
9.6334 

945 
946 
947 
943 
949 

893025 
894916 
896809 
898704 
900601 

843908625 
846590536 
849278123 
851971392 
854670349 

30.7409 
30.757! 
30.7734 
30.7896 
30.8058 

9.8132 
9.8167 
9.8201 
9.8236 
9.8270 

895 
896 
897 
898 
899 

801025 
802816 
804609 
806404 
808201 

716917375 
719323136 
721734273 
724150792 
726572699 

299166 
29.9333 
29.9500 
29.9666 
29.9833 

9.6370 

9.6406 
9.6442 
9.6477 
9.6513 

950 
951 
952 
953 
954 

902500 
904401 
906304 
908209 
910116 

857375000 
86008535  1 
862801408 
865523177 
868250664 

30.8221 
30.8383 
30.8545 
30.8707 
30.8869 

9.8305 
9.8339 
9.8374 
9.8408 
9.8443 

900 
901 
902 
903 
904 

810000 
811801 
813604 
815409 
817216 

729000000 
731432701 
733870808 
736314327 
738763264 

30.000C 
30.0167 
30.0333 
30.0500 
30.0666 

9.6549 
9.6585 
9.6620 
9.6656 
9.6692 

955 
956 
957 
953 
959 

912025  870983875 
913936873722816 
915849876467493 
917764879217912 
919681  831974079 

30.903  1 
30.9192 
30.9354 
30.9516 
30.9677 

9.8477 
9.8511 
9.8546 
9.8580 
9.8614 

905 
906 
907 
908 
909 

819025 
820836 
822649 
824464 
826281 

741217625 
743677416 
746142643 
743613312 
751089429 

30.0832 
30.099£ 
30.1164 
30.133C 
30.1496 

9.6727 
9.6763 
9.6799 
9.6834 
9.6870 

960 
961 
962 
963 
964 

921600 
923521 
925444 
927369 
92929C 

884736000 
887503681 
890277128 
893056347 
895841344 

30.9839 
3  1  .0000 
31.0161 
31.0322 
31.0483 

9.8643 
9.8683 
9.8717 
9.8751 
9.8785 

910 
911 
912 
913 
914 

828100 
82992  1 
83  1  744 
833569 
835396 

75357100C 
756058031 
758550523 
761048497 
763551944 

30.1662 
30.1825 
30.1993 
30.2159 
30.2324 

9.6905 
9.6941 
9.6976 
9.7012 
9.7047 

965 
966 
967 
963 
969 

931225 
933156 
935089 
937024 
938961 

398632125 
901428696 
904231063 
907039232 
909853209 

3  1  .0644 
3  1  .0805 
3  1  .0966 
31.1127 
31.1288 

9.8819 
9.8854 
9.8888 
9.8922 
9.8956 

915 
916 
917 
918 
919 

837225 
839056 
840889 
842724 
844561 

766060875 
763575296 
771095213 
773620632 
776151559 

30.2490 
30.2655 
30.2S2C 
30.2935 
30.3150 

9.7032 
9.7113 
9.7153 
9.7183 
9.7224 

970 
971 
972 
973 
974 

940900 
942841 
944784 
946729 
948676 

912673000 
915498611 
918330048 
921167317 
924010424 

31.1443 
31.1609 
3  1  .  1  769 
31.1929 
3  1  .2090 

9.8990 
9.9024 
9.9058 
9.9092 
9.9126 

920 
921 
922 
923 
924 

846400 
848241 
850084 
851929 
853776 

778688000 
781229961 
783777443 
786330467 
78&889024 

30.3315 
30.3480 
30.3645 
30.3809 
30.3974 

9.7259 
9.7294 
9.7329 
9.7364 
9.7400 

975 
976 
977 
978 
979 

950625 
952576 
954529i 
956484' 
95844  li 

926859375 
929714176 
932574833 
935441352 
938313739 

31.2250 
31.2410 
31.2570 
31.2730 
31.2890 

99160 
99194 
9.9227 
9.9261 
9.9293 

USEFUL  TABLES  FOR  MARINE  ENGINEERS 


239 


No. 

Square. 

Cube. 

Sq. 
Root. 

Cube 
Root. 

No. 

Square. 

Cube. 

Sq. 
Root. 

Cube 
Root. 

"980 

960400 

941  192000 

31.3050 

9.9329 

1033 

1071225 

1108717875 

32.1714 

10.1153 

981 

962361 

944076141 

31.3209 

9.9363 

1036 

10732% 

1111934656 

32  1870 

10  1186 

932 
983 

964324 
966289 

946966168 
949862087 

31.3369 
31.3528 

9.93% 
9.9430 

1037 
1038 

1075369  1115157653 
1077444  1  1  18386872 

32.2025 
32.2180 

10J218 
10  1251 

984 

968256 

952763904 

31.3688 

9.9464 

1039 

1079521 

1121622319 

32.2335 

10.1283 

935 

970225 

955671625 

31.3847 

9.9497 

1040 

1081600 

1124864000 

32.2490 

10.1316 

986 

972196 

958585256 

31.4006 

9.9531 

1041 

1083681 

1128111921 

322645 

10  1343 

087 

974169 

96150430331.4166 

9.9565 

1042 

1085764 

1131366033 

32.2800 

10.1381 

933 

976144 

964430272 

31.4325 

9.9598 

1043 

1087849 

1134626507 

32.2955 

10.1413 

939 

978121 

967361569 

31.4484 

9.%32 

1044 

1089936 

1137893184 

32.3110 

10.1446 

990 

980100 

970299000 

31.4643 

9.9666 

1045 

1092025 

1141166125 

32.3265 

10.1478 

991 

932081 

973242271 

31.4802 

9.9699 

1046 

1094116 

1144445336 

32.3419 

10.1510 

992 

934064 

976191438 

31.4960 

9.9733 

1047 

10%209 

1147730323 

32  3574 

10.1543 

993 

936049 

979146657 

31.5119 

9.9766 

1043 

1098304 

1151022592 

32.3723 

10.1575 

994 

988036 

932107784 

31.5278 

9.9800 

1049 

1100401 

1  154320649 

32.3883 

10.1607 

995 

990025 

935074875 

31.5436 

9.9833 

1050 

1  102500 

1157625000 

32.4037 

10.1640 

996 

992016 

933047936 

31.5595 

9.9366 

1051 

1104601 

1160935651 

32.4191 

10.1672 

997 

994009 

991026973 

31.5753 

9.9900 

1052 

1106704 

1164252603 

32.4345 

10.1704 

993 

996004 

99401  1992 

31.5911 

99933 

1053 

1108309 

1167575877 

324500 

10.1736 

999 

993001 

997002999 

31.6070 

9.9%; 

1054 

1110916 

1170905464 

32.4654 

10.1769 

1000 

1000000 

100000000C 

31.6223 

10.0000 

1055 

1113025 

1174241375 

32.4803 

10  1801 

1001 

1002001 

1003003001 

31.6336 

10.0033 

1056 

1115136 

1177583616 

32.4%2 

10.1833 

1002 

1004004 

1006012003 

31.6544 

10.006/ 

1057 

1117249 

1180932193 

32.5115 

10.1865 

1003 

1006009 

1009027027 

31.6702 

100100 

1053 

1119364 

1184287112 

32.5269 

10.1897 

1004 

1008016 

1012048064 

31.636C 

10.0133 

1059 

1121481 

1  187648379 

32.5423 

10.1929 

1005 

1010025 

1015075125 

31.7017 

100166 

1060 

1123600 

1191016000 

32.5576 

10.1%1 

1006 

1012036 

1018108216 

31.7175 

10.0200 

1061 

1125721 

1194389981 

32.5730 

101993 

1007 

1014049 

1021147343 

31.7333 

10.0233 

1062 

1127844 

1  197770328 

32.5883 

10.2025 

1008 

1016064 

1024192512 

31  7490 

100266 

1063 

1129%9 

1201157047 

32.6036 

10.2057 

1009 

1018031 

1027243729 

31.7648 

10.0299 

1064 

11320% 

1204550144 

32.6190 

10.2039 

1010 

1020100 

1030301000 

31.7805 

10.0332 

1065 

1134225 

120794%25 

32.6343 

10.2121 

1011 

1022121 

1033364331 

31.7%2 

10.0365 

1066 

1136356 

12113554% 

326497 

10.2153 

1012 

1024144 

1036433728 

31.8119 

10.0398 

1067 

1138489 

1214767763 

32.6650 

10.2185 

1013 

1026169 

1039509197 

31.8277 

100431 

1063 

1  140624 

1218186432 

32.6803 

10.2217 

1014 

10281% 

1042590744 

31.8434 

10.0465 

1069 

1  142761 

1221611509 

32.6956 

10.2249 

1015 

1030225 

1045678375 

31.8591 

100493 

1070 

1144900 

1225043000 

32.7109 

10.2281 

1016 

1032256 

10487720% 

31.8743 

10.0531 

1071 

1  147041 

1228480911 

32.7261 

10.2313 

1017 

1034239 

1051871913 

31.8904 

10.0563 

1072 

1149184 

1231925248 

32.7414 

10.2345 

1013 

1036324 

1054977832 

31.9061 

10.05% 

1073 

1151329 

1235376017 

32.7567 

10.2376 

1019 

1033361 

1053089859 

31.9218 

10.0629 

1074 

1153476 

1238833224 

32.7719 

10.2403 

1020 

1040400 

1061208000 

31.9374 

100662 

107« 

1155625 

1242296875 

32.7872 

10.2440 

1021 

1042441 

1064332261 

31.9531 

10.0695 

107o 

1157776 

1245766976 

32.8024 

10.2472 

1022 

1044434 

1067462648 

31.9687 

10.0723 

1077 

1159929 

1249243533 

32.8177 

10  2503 

1023 

1046529 

1070599167 

31.9844 

10.0761 

1078 

1162084 

125272655232.8329 

10.2535 

1024 

1043576 

1073741824 

32.0000 

10.0794 

1079 

1  164241 

1256216039 

32.8481 

10.2567 

1025 

1050525 

1076890625 

32.0156 

10.0326 

1030 

1166400 

1259712000 

32.8634 

10.2599 

1026 

1052676 

1030045576 

32.0312 

100359 

1031 

1  163561 

1263214441 

32.8786 

10.2630 

1027 

1054729 

1033206683 

32.0468 

10.0892 

1032 

1170724 

1266723368 

32.8933 

10.2662 

1028 

1056734 

1036373952 

320624 

10.0925 

1033 

1172389 

1270238787 

32.9090 

10.2693 

1029 

1053341 

1089547389 

32.0780 

10.0957 

1034 

1175056 

1273760704 

32.9242 

10.2725 

1030 

1060900 

1092727000 

320936 

10.099fi 

1035 

1177225 

1277289125 

32.9393 

10  2757 

1031 

1062961 

1095912791 

32  1092  10  1023 

1036 

1179396 

1280824056 

32.9545 

10.2783 

1032 

1065024 

1099104768 

32.1243  10.1055 

1087 

1181569 

1284365503 

32%97 

10.2820 

1033 

1067089 

1  102302937 

32.1403  10.1088 

1038 

1183744 

1287913472 

32.9843 

10.2851 

1034 

1069156 

1  105507304 

32.1559'10.1121 

1089 

1185921 

1291467%9 

330000 

10.2883 

240  MC  ANDREW'S  FLOATING  SCHOOL 

CIRCUMFERENCES  AND  AREAS  OF  CIRCLES. 


Diam. 

Circum. 

Area. 

Diam 

Circum. 

Area. 

Diam 

Circum. 

Area. 

1/64 

.  04909 

.00019 

23/8 

7.4613 

4.4301 

61/8 

19.242 

29   465 

V32 

.09818 

.00077 

7/16 

7.6576 

4.6664 

V4 

19.635 

ZV  .  *fO  J 

30  680 

3/64 

.14726 

.00173 

V2 

7.8540 

4.9087 

3/8 

20.028 

31    919 

Vl6 

.19635 

.00307 

9/16 

8.0503 

5.1572 

1/2 

20.420 

33    1  83 

3/32 

.29452 

.  00690 

5/8 

8.2467 

5.4119 

5/8 

20.813 

34  472 

1/8 

.39270 

.01227 

8.4430 

5.6727 

3/4 

21.206 

35   785 

5/32 

.  49087 

.01917 

a/? 

8.6394 

5.9396 

7/8 

21.598 

37!  122 

3/16 

.  58905 

.02761 

13/16 

8.8357 

6.2126 

7. 

21.991 

38  485 

7/32 

.68722 

.03758 

7/8 

9.0321 

6.4918 

Vs 

22.384 

39^871 

15/16 

9.2284 

6.7771 

22.776 

41    282 

1/4 

.78540 

.  04909 

3/8 

23  .  1  69 

42  '.  1  1  8 

9/32 

.88357 

.06213 

3. 

9.4248 

7  .  0686 

!/•> 

23.562 

44    ]  79 

5/16 

.98175 

.07670 

Vie 

9.6211 

7.3662 

58 

23.955 

45   664 

H/32 

.0799 

.09281 

Vs 

9.8175 

7  .  6699 

3/4 

24.347 

47!  173 

3/8 

.1781 

.11045 

3/16 

10  014 

7.9798 

7/8 

24  740 

48  '.  707 

13/32 

.2763 

.12962 

V4 

10.210 

8.2958 

8. 

25.133 

50.265 

7/16 

.3744 

.15033 

5/16 

10.407 

8.6179 

1/8 

25.525 

51    849 

15/32 

.4726 

.17257 

3/8 

10.603 

8  .  9462 

25.918 

53   455 

7/16 

10.799 

9.2806 

3/8 

26.311 

55   088 

V2 
17/32 

.5708 
.6690 

.19635 
.22166 

V2 
9/16 

10.996 
11.192 

9  .  62  1  1 
9.9678 

V2 
5/8 

26.704 
27.096 

56.  '745 
58  426 

9/16 

.7671 

.24850 

5/8 

1  1  .  388 

10.321 

3/4 

27.489 

60.  132 

19/32 

.8653 

,  27688 

n/ie 

11.585 

10.680 

7g 

27  882 

61  ^862 

5/8 

.9635 

.  30680 

3/4 

11.781 

11.045 

9. 

28.274 

63   617 

21/32 

2.0617 

.33824 

13/16 

11.977 

11.416 

1/8 

28.667 

65   397 

11/16 

2.1598 

.37122 

7/8 

12.174 

1  1  .  793 

1/4 

29.060 

67   201 

23/32 

2.2580 

.40574 

15/16 

12.370 

12.177 

3/8 

29.452 

69.029 

4. 

12.566 

12.566 

1/2 

29  845 

70.882 

3/4 

2.3562 

.44179 

Vl6 

12.763 

1  2  .  962 

5/8 

30.238 

72.760 

23/32 

2.4544 

.47937 

1/8 

12.959 

13.364 

3/4 

30.631 

74  662 

13/16 

2.5525 

.51849 

3/16 

13.155 

13.772 

7/8 

31    023 

76.589 

27/32 

2.6507 

.55914 

1/4 

13.352 

14.186 

10. 

31.416 

78^540 

7/8 

2.7489 

.60132 

5/16 

13.548 

14.607 

31    809 

80  516 

29/32 

2.8471 

.  64504 

3/8 

13.744 

15.033 

1/4 

32.201 

82.516 

15/ig 

2.9452 

.  69029 

7/16 

13.941 

15.466 

3/8 

32.594 

84  541 

31/32 

3.0434 

.73708 

1/2 

14.137 

1  5  .  904 

1/2 

32.987 

86.590 

9/16 

14.334 

16.349 

5/8 

33.379 

88.664 

1. 

3.1416 

.7854 

5/8 

14.530 

1  6  .  800 

3/4 

33.772 

90.763 

Vl6 

3.3379 

.8866 

14.726 

17.257 

7/8 

34.165 

92  .  886 

1/8 

3.5343 

.9940 

9/4 

14.923 

17.721 

11. 

34.558 

95.033 

3/16 

3.7306 

.1075 

13/16 

15.119 

18.  190 

Vs 

34.950 

97.205 

V4 

3.9270 

.2272 

7/8 

15.315 

18.665 

1/4 

35.343 

99.402 

5/16 

4.1233 

.3530 

13/16 

15.512 

19.  147 

3/8 

35.736 

101.62 

3/8 

4.3197 

.4849 

5. 

1  5  .  708 

19.635 

36.  128 

103.87 

7/16 

4.5160 

.6230 

Vl6 

1  5  .  904 

20.  129 

5/8 

36.521 

106.14 

1/2 

4.7124 

.7671 

Vs 

16.  101 

20.629 

3/4 

36.914 

108.43 

9/16 

4.9087 

.9175 

3/16 

16.297 

21.135 

7/8 

37.306 

110.75 

5/8 

5.1051 

2.0739 

1/4 

16.493 

2  1  .  648 

12. 

37.699 

113.10 

H/16 

5.3014 

2.2365 

5/16 

16.690 

22.166 

1/8 

38.092 

115.47 

^3/4 

5.4978 

2.4053 

3/8 

16.886 

22.691 

38.485 

117.86 

13,  16 

5.6941 

2.5802 

7/16 

17.082 

23.221 

3/8 

38.877 

120.28 

7/8 

5  .  8905 

2.7612 

1/2 

17.279 

23.758 

1/2 

39.270 

122.72 

15/16 

6.0868 

2.9483 

9/16 

17.475 

24.301 

5/8 

39.663 

125.19 

5/8 

17.671 

24.850 

3/4 

40.055 

127.68 

2. 

6.2832 

3.1416 

n/16 

1  7  .  868 

25.406 

7/8 

40.448 

130.19 

1/16 

6.4795 

3.3410 

3/4 

18.064 

25.967 

13. 

40.841 

132.73 

1/8 

6.6759 

3.5466 

13/16 

18.261 

26.535 

1/8 

41.233 

135  30 

3/16 

6.8722 

3.7583 

7/8 

18.457 

27.109 

1/4 

41.626 

137.89 

V4 

7  .  0686 

3.9761 

15/16 

18.653 

27  .  688 

3/8 

42.019 

140.50 

5/16 

7.2649 

4.2000 

18.850 

28.274 

1/2 

42.412 

143.  14 

Republished   by   permission   of   Messrs.   John   Wiley  &  Sons,    Inc. 
from    Kent's   Mechanical   Engineers   Pocket- Book. 


USEFUL  TABLES   FOR  MARINE  ENGINEERS 


241 


Diara. 

Circura. 

Area. 

Diam. 

Circum. 

Area. 

Diam. 

Circum. 

Area. 

135/8 

42.804 

145.80 

217/8 

68.722 

375.83 

30  1/8 

94.640 

712  76 

3/A 

43.  197 

148.49 

22. 

69.115 

380.  13 

V4 

95.033 

7  1  8  69 

7/8 

43.590 

1  5  1  .  20 

178 

69.508 

384.46 

3/8 

95.426 

724  64 

14. 

43.982 

153.94 

1/4 

69.900 

388.82 

1/2 

95.819 

730  '62 

1/8 

44.375 

156.70 

3/8 

70.293 

393.20 

5/8 

96.211 

736  62 

i// 

44.768 

159.48 

V* 

70.686 

397.61 

3/4 

96.604 

742  64 

3/8 

45.160 

162.30 

5/8 

71.079 

402.04 

7/8 

96.997 

748.69 

1/2 

45.553 

165.13 

3/4 

71.471 

406.49 

31. 

97.389 

754  77 

5/8 

45.946 

1  67  .  99 

7/8 

7  1  .  864 

410.97 

1/8 

97.782 

760  87 

3/4 

46.338 

170.87 

23. 

72.257 

415.48 

1/4 

98.175 

766  99 

7/8 

46.731 

173.78 

V8 

72.649 

420.00 

3/8 

98.567 

773.  14 

15. 

47.124 

176.7! 

1/4 

73.042 

424.56 

V2 

98.960 

779  31 

1/8 

47.517 

179.67 

3/8 

73.435 

429.13 

5/8 

99.353 

785  51 

1/4 

47.909 

182.65 

1/2 

73.827 

433.74 

3/4 

99.746 

791    73 

3/8 

48.302 

185.66 

5/8 

74.220 

438.36 

7/8 

100.138 

797  98 

Va 

48.695 

188.69 

3/4 

74.613 

443.01 

32. 

100.531 

804.25 

5/3 

49.037 

191.75 

7/8 

75.006 

447.69 

V8 

100.924 

810.54 

3/4 

49.480 

194.83 

24. 

75.398 

452.39 

1/4 

101.316 

816.86 

7/8 

49.873 

197.93 

V8 

75.791 

457.11 

3/8 

101.709 

823.21 

16. 

50.265 

201.06 

1/4 

76.  184 

461.86 

1/2 

102.102 

829.58 

1/8 

50.658 

204.22 

3/8 

76.576 

466.64 

5/8 

1  02  .  494 

835.97 

V4 

51.051 

207.39 

1/2 

76.969 

47  1  .  44 

3/4 

102.887 

842.39 

3/8 

51.414 

210.60 

5/8 

77.362 

476.26 

7/8 

103.280 

848.83 

1/2 

51.836 

213.82 

3/4 

77.754 

431.11 

33. 

103.673 

855.30 

5/8 

52.229 

217.08 

7/8 

78.147 

485.98 

Vg 

104.065 

861.79 

3/4 

52.622 

220.35 

25. 

78.540 

490.87 

1/4 

104.458 

868.31 

7/8 

53.014 

223.65 

1/8 

78.933 

495.79 

3/8 

104.851 

874.85 

17. 

53.407 

226.98 

1/4 

79.325 

500.74 

1/2 

105.243 

881.41 

Vs 

53.800 

230.33 

3/8 

79.718 

505.71 

5/8 

105.636 

888.00 

1/4 

54.  192 

233.71 

1/9 

80.111 

510.71 

3/4 

106.029 

894  .  62 

3/8 

54.585 

237.10 

5/8 

80.503 

515.72 

7/8 

106.421 

901.26 

1/2 

54.978 

240.53 

3/4 

80.896 

520.77 

34. 

106.814 

907  .  92 

5/8 

55.371 

243.98 

7/8 

81.289 

525.84 

1/8 

107.207 

914.61 

3/4 

55.763 

247.45 

26. 

81.681 

530.93 

1/4 

107.600 

921.32 

7/8 

56.156 

250.95 

1/8 

82.074 

536.05 

3/8 

107.992 

928.06 

18. 

56.549 

254.47 

1/4 

82.467 

541.19 

1/2 

108.385 

934.82 

1/8 

56  941 

258  02 

3/8 

82.860 

546.35 

5/8 

108.778 

941.61 

1/4 

57.334 

261.59 

1/9 

83.252 

551.55 

3/4 

109.170 

948.42 

3/8 

57.727 

265.18 

5/8 

83.645 

556.76 

7/8 

109.563 

955.25 

v" 

58.119 

268.80 

3/4 

84.038 

562.00 

35. 

109.956 

962.11 

5/8 

58.512 

272.45 

7/8 

84.430 

567.27 

1/8 

110.348 

969  .  00 

3/4 

58.905 

276.12 

27. 

84.823 

572.56 

V4 

110.741 

975.91 

7/8 

59.298 

279.81 

Vs 

85.216 

577.87 

3/8 

111.134 

982  .  84 

19. 

59.690 

283.53 

1/4 

85.608 

583.21 

1/2 

111.527 

939.80 

1/8 

60.083 

287.27 

3/8 

86.001 

588.57 

5/8 

111.919 

996.78 

1/4 

60  476 

291.04 

1/9 

86.394 

593.96 

3/4 

112.312 

1003.8 

S/g 

60.868 

294.83 

5/8 

86.786 

599.37 

7,8 

112.705 

1010.8 

1/9 

61.261 

298.65 

3/4 

87.179 

604.81 

36. 

113.097 

1017.9 

5/g 

61    654 

302.49 

7/8 

87.572 

610.27 

Vs 

1  1  3  .  490 

1025.0 

3/4 

62  046 

3C5  35 

28. 

87.965 

615.75 

1/4 

113.883 

1032.1 

7/8 

62.439 

310.24 

1/8 

88.357 

621.26 

3/8 

114.275 

1039.2 

20. 

62  832 

314.16 

1/4 

88.750 

626.80 

1/2 

114.668 

1046.3 

1/8 

63.225 

318.10 

Jj/8 

89.143 

632.36 

5/8 

115.061 

1053.5 

1/4 

63  617 

322  06 

1/9 

89.535 

637.94 

3/4 

115.454 

1060.7 

3/8 

1/9 

64!010 
64  403 

326.05 
330  06 

5/8 

3/4 

89.928 
90.321 

643.55 
649.18 

7/8 

37. 

115.846 
116.239 

1068.0 
1075.2 

5    Q 

64.795 

334   10 

7/8 

90.713 

654.84 

1/8 

116.632 

1032.5 

3/5 

65    188 

338.16 

29. 

91.106 

660.52 

1/4 

117.024 

1089.8 

7,8 

65  581 

342  25 

1/8 

91.499 

666.23 

3/8 

117.417 

1097.1 

21. 

65.973 

346.36 

1/4 

91.892 

671.96 

1/2 

117.810 

1104.5 

Vg 

1/4 
3  'g 

66.366 
66.759 
6>    1  52 

350.50 
354.66 
358  84 

8 

5/8 

92  .  284 
92.677 
93.070 

677.71 
683  .  49 
689.30 

5/8 
3/4 
7/8 

1  18.202 
118.596 
118.988 

\\\9'.2 
1126.7 

1/2 
-8 
3  4 

67!  544 
67.937 
63.330 

363.05 
367.28 
371.54 

3/4 
7/8 
30. 

93  .  462 
93.855 
94.248 

695.13 
700.98 
706  .  86 

38. 

V8 

1/4 

119.381 
119.773 
120.166 

1  134.  1 
1141.6 
1149.1 

242 


MC  ANDREW'S  FLOATING  SCHOOL 


Dlam 

Circum. 

Area. 

Diara 

Circum. 

Area. 

Diam 

Circum. 

Area. 

383/8 

120.559 

1156.6 

465/8 

146.477 

1707.4 

547/j, 

172.395 

2365.0 

1/2 

120.951 

1164.2 

3/4 

146.869 

1716.5 

55. 

172.788 

2375.8 

5/8 

121.344 

1171.7 

7/8 

147.262 

1725.7 

1/8 

173.  180 

2386.6 

3/4 

121.737 

1179.3 

47. 

147.655 

1734.9 

1/4 

173.573 

2397.5 

7/8 

122.  129 

1186.9 

i/s 

148.048 

1744.2 

3/8 

1  73  .  966 

2408.3 

39. 

122.522 

1194.6 

1/4 

148.440 

1753.5 

1/2 

174.358 

2419.2 

1/8 

122.915 

1202.3 

3/8 

148.833 

1762.7 

5/8 

174.751 

2430.  1 

1/4 

123.308 

1210.0 

Va 

149.226 

1772.1 

3/4 

175.  144 

2441.  1 

3/8 

123.700 

1217.7 

5/8 

149.618 

1781.4 

7/8 

175.536 

2452.0 

1/2 

124.093 

1225.4 

3/4 

150.011 

1790.8 

56. 

175.929 

2463.0 

5/8 

124.486 

1233.2 

7/8 

150.404 

1800.1 

1/8 

176.322 

2474.0 

3/4 

124.878 

1241.0 

48. 

150.796 

1809.6 

1/4 

176.715 

2485.0 

7/a 

125.271 

1248.8 

V8 

151.189 

1819.0 

3/8 

177.  107 

2496   1 

40. 

125.664 

1256.6 

1/4 

151.582 

1828.5 

Va 

177.500 

2507.2 

1/8 

126.056 

1264.5 

3/8 

151.975 

1837.9 

5/8 

177.893 

2518.3 

V4 

126.449 

1272.4 

1/2 

152.367 

1847.5 

3/4 

178.285 

2529.4 

3/8 

126.842 

1280.3 

5/8 

152.760 

1857.0 

7/8 

178.678 

2540.6 

1/9 

127.235 

1288.2 

3/4 

153.153 

1866.5 

57. 

179.071 

2551.8 

5/8 

127.627 

1296.2 

7/8 

153.545 

1876.1 

1/8 

179.463 

2563.0 

3/4 

128.020 

1304.2 

49. 

153.938 

1885.7 

1/4 

179.856 

2574.2 

7/8 

128.413 

1312.2 

1/8 

154.331 

1895.4 

3/8 

180.249 

2585.4 

41. 

128.805 

1320.3 

1/4 

154.723 

1905.0 

Va 

180.642 

2596.7 

1/8 

129.198 

1328.3 

3/8 

155.116 

1914.7 

5/8 

181.034 

2608.0 

V4 

129.591 

1336.4 

1/2 

155.509 

1924.4 

3/4 

181.427 

2619.4 

3/8 

129.983 

1344.5 

5/8 

155.902 

1934.2 

7/8 

181.820 

2630.7 

1/2 

130.376 

1352.7 

3/4 

156.294 

1943.9 

58. 

182.212 

2642.  1 

5/8 

130.769 

1360.8 

7/8 

156.637 

1953.7 

1/8 

182.605 

2653.5 

3/4 

131.161 

1369.0 

50. 

157.080 

1963.5 

V4 

182.998 

2664.9 

7/8 

131.554 

1377.2 

1/8 

157.472 

1973.3 

3/8 

183.390 

2676.4 

42. 

131.947 

1385.4 

1/4 

157.865 

1983.2 

Va 

183.783 

2687.8 

1/8 

132.340 

1393.7 

M 

158.258 

1  993  .  1 

5/8 

184.176 

2699.3 

1/4 

132.732 

1402.0 

Va 

158.650 

2003.0 

3/4 

184.569 

2710.9 

3/8 

133.125 

1410.3 

5/8 

159.043 

2012.9 

7/8 

184.961 

2722.4 

1/9 

133.518 

1418.6 

3/4 

159.436 

2022.8 

59. 

185.354 

2734.0 

5/8 

133.910 

1427.0 

7/8 

159.829 

2032.8 

1/8 

185.747 

2745.6 

3/4 

134.303 

1435.4 

51. 

160.221 

2042.8 

1/4 

186.139 

2757.2 

7/8 

134.696 

1443.8 

1/8 

160.614 

2052.8 

3/8 

186.532 

2768.8 

43. 

135.088 

1452.2 

1/4 

161.007 

2062  .  9 

1/2 

186.925 

2780.5 

1/8 

135.481 

1460.7 

3/8 

161.399 

2073.0 

$ 

187.317 

2792.2 

V4 

135.874 

1469.1 

Va 

161.792 

2083  .  1 

3/4 

187.710 

2803.9 

3/8 

136.267 

1477.6 

5/8 

162.185 

2093.2 

7/8 

188.  103 

2815.7 

1/2 

136.659 

1486.2 

3/4 

162.577 

2103.3 

60. 

188.496 

2827.4 

5/8 

137.052 

1  494  .  7 

7/8 

162.970 

2113.5 

1/8 

188.888 

2839.2 

3/4 

137.445 

1503.3 

69. 

163.363 

2123.7 

1/4 

189.281 

2851.0 

7/8 

137.837 

1511.9 

V8 

163.756 

2133.9 

3/8 

189.674 

2862.9 

44. 

138.230 

1520.5 

1/4 

164.148 

2144.2 

1/2 

190.066 

2874.8 

1/8 

138.623 

1529.2 

3/8 

164.541 

2154.5 

5/8 

190.459 

2886.6 

!/4 

139.015 

1537.9 

1/2 

164.934 

2164.8 

3/4 

190.852 

2898.6 

3/8 

139.408 

1546.6 

5/8 

165.326 

2175.1 

7/8 

191.244 

2910.5 

1/9 

139.801 

1555.3 

3/4 

165.719 

2185.4 

61. 

191.637 

2922.5 

5/8 

140.194 

1564.0 

7/8 

166.112 

2195.8 

!/8 

192.030 

2934.5 

3/4 

140.586 

1572.8 

53. 

166.504 

2206.2 

1/4 

192.423 

2946.5 

7/8 

140.979 

1581.6 

1/8 

166.897 

2216.6 

3/8 

192.815 

2958.5 

45. 

141.372 

1590.4 

1/4 

167.290 

2227.0 

1/2 

193.208 

2970.6 

1/8 

141.764 

1599.3 

3/8 

167.683 

2237.5 

5/8 

193.601 

2982  .  7 

!/4 

142.157 

1608.2 

1/2 

168.075 

2248.0 

34 

193.993 

2994.8 

3/8 

142.550 

1617.0 

5/8 

168.468 

2258.5 

7/8 

194.386 

3006.9 

1/2 

142  942 

1626.0 

3/4 

168.861 

2269.  1 

62. 

194.779 

3019.1 

5/8 

143.335 

1634.9 

7/8 

169.253 

2279.6 

1/8 

195.171 

3031.3 

3/4 

143.728 

1643.9 

54. 

169.646 

2290.2 

1/4 

195.564 

3043.5 

7/8 

144   121 

1652.9 

l/8 

170.039 

23C0.8 

3/8 

195.957 

3055.7 

46. 

144.513 

1661.9 

1/4 

170.431 

2311.5 

Va 

196.350 

3068.0 

1/8 

144.906 

1670.9 

3/8 

170.824 

2322.1 

5/8 

196.742 

3080.3 

1/4 

145.299 

1680.0 

V2 

171.217 

2332.8 

3/4 

197.135 

3092.6 

3/8 

145.691 

1689.5 

5/8 

1  7  1  .  609 

2343.5 

7/8 

197.528 

3104  9 

1/2 

146.084 

1698,2 

3/4 

1  72  .  002 

2354.3 

63. 

197.920 

3117.2 

USEFUL  TABLES  FOR  MARINE  ENGINEERS 


243 


Diam. 

Circum. 

Area. 

Diam 

Circum. 

Area. 

Diam 

Circum. 

Area. 

63  Vs 

198.313 

3129.6 

71  a/s 

224.  23  i 

4001.  1 

795/a 

250.  149 

4979.5 

1/4 

198.706 

3142.0 

1/2 

224.624 

4015.2 

3/4 

250  542 

4995  2 

3/8 

199.098 

3154.5 

5/8 

225.017 

4029.2 

7/8 

250.935 

5010  9 

V2 

199.491 

3166.9 

3/4 

225.409 

4043.3 

80. 

251.327 

5026  '5 

5/8 

199.884 

3179.4 

7/8 

225.802 

4057.4 

1/8 

251.720 

5042  '3 

3/4 

200.277 

3191.9 

73. 

226.195 

407  1  .  5 

1/4 

252.113 

5058  0 

7/8 

200.669 

3204.4 

1/8 

226.587 

4085.7 

3/8 

252  506 

5073  8 

64. 

201.062 

3217.0 

V4 

226.980 

4099.8 

!/2 

252.898 

5089.6 

i/s 

201.455 

3229.6 

3/8 

227.373 

4114.0 

5/8 

253.291 

5105  4 

1/4 

201.847 

3242.2 

1/2 

227.765 

4128.2 

3/4 

253.684 

5121   2 

3/8 

202.240 

3254.8 

5/8 

223.158 

4142.5 

7/8 

254.076 

5137.1 

Va 

202.633 

3267.5 

3/4 

228.551 

4156.8 

81. 

254.469 

5153.0 

5/8 

203.025 

3280.1 

7/8 

228.944 

4171.1 

1/0 

254.862 

5168  9 

3/4 

203.418 

3292.8 

73. 

229.336 

4185.4 

14 

255.254 

5184.9 

7/8 

203.811 

3305.6 

1/8 

229.729 

4199.7 

3/8 

255.647 

5200.8 

65. 

204.204 

3318.3 

V4 

230.122 

4214.1 

1/2 

256.040 

5216.8 

1/8 

204.596 

3331.1 

3/8 

230.514 

4228.5 

5/8 

256.433 

5232.8 

V4 

204.989 

3343.9 

1/2 

230.907 

4242.9 

3/4 

256.825 

5248.9 

3/8 

205.382 

3356.7 

5/8 

231.303 

4257.4 

7/8 

257.218 

5264.9 

1/2 

205.774 

3369.6 

3/4 

231.692 

4271.8 

82. 

257.611 

5281.0 

5/8 

206.167 

3382.4 

7/8 

232.085 

4286.3 

1/8 

258.003 

5297.1 

3/4 

206.560 

3395.3 

74. 

232.478 

4300.8 

1/4 

258.396 

5313.3 

7/8 

206.952 

3408.2 

1/8 

232.871 

4315.4 

3/8 

258.789 

5329.4 

66. 

207.345 

3421.2 

1/4 

233.263 

4329.9 

1/2 

259.181 

5345.6 

Vi 

207.738 

3434.2 

3/8 

233.656 

4344.5 

5/8 

259.574 

5361.8 

V* 

208.131 

3447.2 

1/2 

234.049 

4359.2 

3/4 

259.967 

5378.1 

3/8 

208.523 

3460.2 

5/8 

234.441 

4373.8 

7/8 

260.359 

5394.3 

Va 

208.916 

3473.2 

3/4 

234.834 

4388.5 

83. 

260.752 

5410.6 

5/8 

209.309 

3486.3 

7/8 

235.227 

4403  .  1 

1/8 

261.145 

5426.9 

3/4 

209.701 

3499.4 

75. 

235.619 

4417.9 

1/4 

261.538 

5443.3 

7/8 

210.094 

3512.5 

1/8 

236.012 

4432.6 

3/8 

261.930 

5459.6 

67. 

210.487 

3525.7 

1/4 

236.405 

4447.4 

V2 

262.323 

5476.0 

Vs 

210.879 

3538.8 

3/8 

236.798 

4462.2 

5/8 

262.716 

5492.4 

V4 

211.272 

3552.0 

1/2 

237.190 

4477.0 

3/4 

263.108 

5508.8 

3/8 

211.665 

3565.2 

5/8 

237.583 

4491.8 

7/8 

263.501 

5525.3 

V2 

212.058 

3578.5 

3/4 

237.976 

4506.7 

84. 

263.894 

5541.8 

5/8 

212.450 

3591.7 

7/8 

238.368 

4521.5 

Vs 

264.286 

5558.3 

3/4 

212.843 

3605.0 

76. 

233.761 

4536.5 

1/4 

264.679 

5574.  8 

7/8 

213.236 

3618.3 

1/8 

239.154 

4551.4 

3/8 

265.072 

5591.4 

68. 

2  1  3  .  628 

3631.7 

V4 

239.546 

4566.4 

!/2 

265.465 

5607.9 

1/8 

214.021 

3645.0 

3/8 

239.939 

4581.3 

5/8 

265.857 

5624.5 

1/4 

214.414 

3653.4 

!/2 

240.332 

4596.3 

3/4 

266.250 

5641.2 

3/8 

214.806 

3671.8 

5/8 

240.725 

4611.4 

7/8 

266.643 

5657.8 

1/2 

215.  199 

3685.3 

3/4 

241.117 

4626.4 

85. 

267.035 

5674.5 

5/8 

215.592 

3698.7 

7/8 

241.510 

4641.5 

1/8 

267.428 

5691.2 

3/4 

215.984 

3712.2 

77. 

241.903 

4656.6 

1/4 

267.821 

5707.9 

7/8 

216.377 

3725.7 

1/8 

242.295 

4671.8 

3/8 

268.213 

5724.7 

69. 

216.770 

3739.3 

V4 

242.688 

4686.9 

1/2 

26*.  606 

5741.5 

1/8 

217.163 

3752.8 

3/8 

243.031 

4702.1 

5/8 

263.999 

5758.3 

1/4 

217.555 

3766.4 

1/2 

243.473 

4717.3 

3/4 

269.392 

5775.1 

3/8 

217.948 

3780.0 

5/8 

243.866 

4732.5 

7/8 

269.784 

5791.9 

1/2 

218.341 

3793.7 

3/4 

244.259 

4747.8 

86. 

270.177 

5808.8 

5/8 

218  733 

3807.3 

7/8 

244.652 

4763.1 

V8 

270.570 

5825.7 

3/4 

219.126 

3821.0 

78. 

245.044 

4778.4 

1/4 

270.962 

5842.6 

7/8 

219.519 

3834.7 

1/8 

245.437 

4793.7 

3/8 

271.355 

5859.6 

70. 

219.911 

3848.5 

1/4 

245.830 

4809.0 

1/2 

271.748 

5876.5 

V8 

220.304 

3862.2 

3/8 

246.222 

4824.4 

5/8 

272.140 

5893.5 

1/4 

220.697 

3876.0 

1/9 

246.615 

4839.8 

3/4 

272.533 

5910.6 

3/8 

221.090 

3889.8 

5/8 

247.008 

4855.2 

7/8 

272.926 

5927.6 

!/2 

221.482 

3903.6 

3/4 

247   400 

4870.7 

87. 

273.319 

5944.7 

5/8 

221.375 

3917.5 

7/8 

247.793 

4886.2 

1/8 

273.711 

5961.8 

3/< 

222.268 

3931.4 

79. 

248.  186 

4901.7 

1/4 

274.104 

5978.9 

7/8 

222.660 

3945  3 

*/8 

248.579 

4917.2 

3/8 

274.497 

5996.0 

71. 

223.053 

3959  2 

V4 

248.971     4932.7 

V2 

274.889 

6013.2 

Vs 

223.446 

3973    1 

3/8 

249.364    4948.3 

5/8 

275.282 

6030.4 

V4 

223.838 

3987.1 

1/2 

249.757     4963.9 

3/4 

275.675 

6047.6 

244 


MC  ANDREW'S  FLOATING  SCHOOL 


Diam 

Circum. 

Area. 

Diam 

Circum 

Area. 

Diam 

Circum. 

Area. 

877/8 

276.067 

6064.9 

957/s 

301.200 

7219.4 

130 

408.41 

13273.23 

88. 

276.460 

6082.1 

96. 

301.593 

7238.2 

131 

411.55 

13478  22 

Vs 

276.853 

6099.4 

V8 

301.986 

7257.1 

132 

414.69 

13684.78 

1/4 

277.246 

6116.7 

1/4 

302.378 

7276.0 

133 

417.83 

13892.91 

3/8 

277.638 

6134.1 

3/8 

302.771 

7294.9 

134 

420.97 

14102.61 

V2 

278.031 

6151.4 

1/2 

303.  164 

7313.8 

135 

424.12 

14313.88 

5/8 

278.424 

6168.8 

5/8 

303.556 

7332.8 

136 

427.26 

14526.72 

3/4 

278.816 

6186.2 

3/4 

303.949 

7351.8 

137 

430.40 

14741.  14 

7/8 

279.209 

6203  .  7 

7/8 

304.342 

7370.8 

138 

433.54 

14957.  12 

89. 

279.602 

622  1  .  1 

97. 

304.734 

7389.8 

139 

436.68 

15174.68 

1/8 

279.994 

6238.6 

1/8 

305.127 

7400.9 

140 

439.82 

15393.80 

V4 

280.387 

6256.  1 

1/4 

305.520 

7420.0 

141 

442  .  96 

15614.50 

3/8 

280.780 

6273.7 

3/8 

305.913 

7447.1 

142 

446.11 

15836.77 

V2 

281.173 

6291.2 

yl 

306.305 

7466.2 

143 

449.25 

16060.61 

5/8 

281.565 

6308.8 

5/8 

306.698 

7485  .  3 

144 

452.39 

16286.02 

3/4 

281.958 

6326.4 

3/4 

307.091 

7504.5 

145 

455.53 

16513.00 

7/8 

282.351 

6344.  1 

7/8 

307.483 

7523.7 

146 

458.67 

16741.55 

90. 

282.743 

6361.7 

98. 

307.876 

7543.0 

147 

461.81 

16971.67 

1/8 

283.  136 

6379.4 

V8 

308.269 

7562.2 

148 

464.96 

1  7203  .  36 

1/4 

283.529 

6397.1 

1/4 

30S.661 

7581.5 

149 

468.10 

17436.62 

3/8 

283.921 

6414.9 

3/8 

309.054 

7600.8 

150 

471.24 

17671.46 

V2 

284.314 

6432.6 

1/2 

309.447 

7620.  1 

151 

474.38 

17907.86 

5/8 

284.707 

6450.4 

5/8 

309.840 

7639.5 

152 

477.52 

18145.84 

3/4 

285.100 

6468.2 

3/4 

310.232 

7658.9 

153 

480.66 

18385.39 

7/8 

285.492 

6486.0 

7/8 

310.625 

7678.3 

154 

483.81 

8626.50 

91. 

285.885 

6503.9 

99. 

311.018 

7697.7 

155 

486.95 

8869.19 

1/8 

286.278 

6521.8 

1/8 

311.410 

7717.  1 

156 

490.09 

9113.45 

1/4 

286.670 

6539.7 

1/4 

311.003 

7736.6 

157 

493.23 

9359.28 

3/8 

287.063 

6557.6 

3/8 

312.  196 

7756.1 

158 

496.37 

9606.68 

1/2 

287.456 

6575.5 

1/2 

312.588 

7775.6 

159 

499.51 

9855.65 

5/8 

287.848 

6593.5 

5/8 

312.981 

7795.2 

160 

502.65 

20106.19 

3/4 

288.241 

6611.5 

3/4 

313.374 

7814.8 

161 

505.80 

20358.31 

7/8 

288.634 

6629.6 

7/8 

313.767 

7834.4 

162 

508.94 

20611.99 

93. 

289.027 

6647.6 

100 

314.159 

7854.0 

163 

512.08 

20867.24 

V8 

289.419 

6665  .  7 

101 

317.30 

8011.85 

164 

5  1  5  .  22 

21124.07 

1/4 

289.812 

6683  .  8 

102 

320.44 

8171.28 

165 

518.36 

21382.46 

3/8 

290.205 

6701.9 

103 

323.58 

8332.29 

166 

521.50 

2  1  642  .  43 

1/2 

290.597 

6720.  1 

104 

326.73 

8494.87 

167 

524.65 

21903.97 

5/8 

290.990 

6738.2 

105 

329.87 

8659.01 

168 

527.79 

22167.08 

3/4 

291.383 

6756.4 

106 

333.01 

8824.73 

169 

530.93 

22431.76 

78 

291.775 

6774.7 

107 

336.15 

8992.02 

170 

534.07 

22698.01 

93. 

292.168 

6792.9 

108 

339.29 

9160.88 

171 

537.21 

22965  .  83 

Vi 

292.561 

6811.2 

109 

342.43 

9331.32 

172 

540.35 

23235.22 

V4 

292  954 

6829.5 

110 

345.58 

9503.32 

173 

543.50 

23506.18 

3/8 

293.346 

6847.8 

343.72 

9676.89 

174 

546.64 

23778.71 

V2 

293.739 

6866.  1 

112 

351.86 

9852.03 

175 

549.78 

24052.82 

5/8 

294.132 

6884.5 

113 

355.00 

0028.75 

176 

552.92 

4328.49 

3/4 

294.524 

6902.9 

114 

353.14 

0207.03 

177 

556.06 

4605.74 

r/l 

294.917 

6921.3 

115 

361.28 

0386.89 

178 

559.20 

4884.56 

94. 

295.310 

6939.8 

116 

364.42 

0568.32 

179 

562.35 

5164.94 

1/8 

295  .  702 

6958.2 

117 

367.57 

0751.32 

180 

565.49 

5446.90 

!/4 

296.095 

6976.7 

118 

370.71 

0935.88 

in 

568.63 

5730.^3 

3/8 

296.488 

6995  .  3 

119 

373.85 

1122.02 

182 

571.77 

6015.53 

1/2 

296.881 

7013.8 

120 

376.99 

1309.73 

183 

574.91 

6302.20 

5/8 

297.273 

7032.4 

121 

380.13 

1499.01 

184 

578.05 

6590.44 

34 

297.666 

7051.0 

122 

383.27 

1689.87 

185 

581.19 

6880.25 

7/8 

298.059 

7069.6 

123 

386.42 

1882.29 

186 

584.34 

7171.63 

95. 

298.451 

7088.2 

124 

389.56 

2076.28 

187 

587.48 

7464.59 

1/8 

298.844 

7106.9 

125 

392.70 

2271.85 

188 

590.62 

7759.11 

1/4 

299.237 

7125.6 

126 

395.84 

2468.98 

189 

593  .  76 

8055.21 

3/8 

299  629 

7144.3 

127 

398.98 

2667.69 

190 

596.90 

8352.87 

I/O 

300.022 

7163.0 

128 

402  .  1  2 

2867.96 

191 

600.04 

8652.  11 

5/8 

300.415 

7181.8 

129 

405.27 

3069.81 

192 

603.19 

8952.92 

3/4 

300.807 

7200.6 

USEFUL  TABLES  FOR  MARINE  ENGINEERS  245 

WEIGHT   OF  RODS,  BARS,  PLATES,  TUBES,  AND   SPHERES 
OF  DIFFERENT  MATERIALS. 

Notation:  6  «=  breadth,  t  =  thickness,  s  =  side  of  square.  D  =  ex- 
ternal diameter,  d  =  internal  diameter,  all  in  inches. 

Sectional  areas:  of  square  bars  =  s2;  of  flat  bars  =  U;  of  round  rods 
=  0.7854  £>2;  of  tubes  =  0.7854  (Z>*  -  d2)  =  3.1416  (Dt  -  *»). 

Volume  of  1  foot  in  length:  of  square  bars  =  12s2;  of  flat  bars  =  I2bt- 
of  round  bars  =  9.4248D2;  of  tubes  =  9.4248  (£>2  -  d2)  =  37.699  (Dt  -  t2), 
in  cu.  in. 

Weight  per  foot  length  =  volume  X  weight  per  cubic  inch  of  mate- 
rial. Weight  of  a  sphere  =  diam.3  X  0.5236  X  weight  per  cubic  inch. 


Material. 


d- 
«-OQ 


•32U 


& 

fa 


I- 

•n 


5^_5 


Cast  iron 

Wrought  iron 

Steel 

Copper  &  Bronze 
(copper  and  tin) 


Lead 

Aluminum 

Glass 

Pine  wood,  dry. . 


7.218 

7.7 

7.854 

8.855 

8.393 

11.33 
2.67 
2.62 
0.481 


450. 
480. 
489.6 

552. 

523.2 

709.6 
166.5 
163.4 
30.0 


37.5 

40. 

40.8 

46. 

43.6 

59.1 
13.9 
13.6 
2.5 


31/8 

\y 

3.833 

3.633 

4.93 
1.16 
1  13 
0.21 


31/8 
ft 
3.833 

3.633 

4.93 
1.16 
1.13 
0.21 


.2604 
.2779 
.2833 

.3195 

.3029 

.4106 
.0963 
.0945 
.0174 


15-16 

I. 

1.02 

1.15 

1.09 

1.48 
0.347 
0.34 
1-16 


2.454 
2.618 
2.670 

3.011 

2.854 

3.870 
0.908 
0.891 
0.164 


.1363 
.1455 
.1484 

.1673 

.1586 

.2150 
.0504 
.0495 
.0091 


Weight   per  cylindrical  in., 
last  col.  +  12. 


1   in.  long,  =  coefficient  of  Z>2  in  next  to 


Republished    by  permission   of   Messrs.  John   Wiley  &  Sons,   Inc. 
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branches  of  the  subject.  The  text  is  in  such  plain,  simple 
language  that  any  man  with  an  ordinary  education  can 
easily  understand  it. 

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Marks  and  Davis  Tables 

and  Diagrams  of  the  Thermal  Properties 
of   Saturated  and   Superheated   Steam 

By  Lionel  S.  Marks,  M.M.E.,  Professor  of  Me- 
chanical Engineering,  Harvard  University,  and 
Harvey  N.  Davis,  Ph.D.,  Assistant  Professor  of 
Physics,  Harvard  University.  With  8  illustrations 
and  2  large  folded  diagrams.  Large  8vo.  106  pp. 

Diagrams  Separately:  (1)  Total  Heat-Entropy 
Diagram;  (2)  Total  Heat-Pressure  Diagram.  In 
heavy  Manila  envelope.  Net  40  cents. 

The  chief  features  of  these  new  tables  are  (1)  greater 
accuracy;  (2)  greater  convenience;  (3)  the  addition  of 
large  steam  diagrams  for  the  solution  of  problems. 

(1)  The  principal  error  in  all  former  tables  has  been 
in  the  values  of  the  total  heat  of  saturated  steam  and  in 
the  quantities  deduced  from  the  total  heat.     In  Marks 
and  Davis 's  tables  new  data  for  the  total  heat  of  satura- 
ted steam  are  given  from  investigations  by  one  of  the 
authors,  which  it  is  expected  will  give  the  present  tables 
permanence. 

(2)  The   greater   convenience   of  these   tables   is   es- 
pecially noticeable  in  the  table  of  properties  of  super- 
heated steam,  which  is  so  arranged  that  all  the  properties 
of  any  stated  pressure  are  given  on  one  double  page. 

(3)  The  steam  diagrams,  it  is  believed,  will  greatly 
facilitate   the   solution  of   a  large   number   of  problems 
which  hitherto  have  been  soluble  only  by  laborious  cal- 
culation or  by  methods  of  trial  and  error. 

There  are  other  features  which  will  be  found  to  be  of 
material  value  both  to  engineers  and  scientists. 

"A  remarkably  well  arranged  and  complete  utilisa- 
tion of  the  results  of  the  latest  investigations  on 

the  properties  of  steam Will  be  adopted  as 

the    standard    by    all    careful    computers" — THE 
ENGINEERING  EECORD. 

Longmans,  Green  &  Co. 

Publishers 
Fourth  Avenue  and  30th  St.,  New  York 


(256) 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
BERKELEY 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 

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APR    9  1918 


FEB  '811S27 


50m-7,'16 


UO  I 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


